What is cloaking in advertising, and how can buyers test for it?
Part of MFA avoidance
The short answer
Cloaking is showing one version of a page to crawlers, classifiers and reviewers and a different one to real visitors. A site can pass brand safety and quality scans with a clean page while paying visitors get heavier ads or other topics. Buyers test for it by loading the same page under different conditions and comparing what each view shows.
Key takeaways
- Cloaking reads cues such as the user agent, IP address, referrer, JavaScript support and interaction to decide which version a visitor gets.
- Google Ads treats cloaking as an egregious circumventing systems violation, with account suspension on detection and without prior warning.
- Some differences are legitimate: language, location, offers, connection speed and responsive layouts change pages without hiding anything.
- A buyer's test compares views across device, entry path and network, and a confirmed case belongs on the exclusion list, not in a review queue.
What is cloaking in advertising?
Cloaking appears on both sides of an ad. On the advertiser side, a landing page shows Google's reviewers a compliant page and shows people something else. On the publisher side, which matters to a media buyer, a site shows crawlers and verification scans a tidy editorial page while visitors, such as those arriving from paid links, see a page built to show ads. In both cases the goal is the same: pass an automated check with content that real users never see.
Definition
- Cloaking
- Serving different content to automated reviewers and to real visitors in order to hide what the page is, or what it does, from the reviewer.
Google's Google Ads cloaking policy (opens in a new tab) describes it as "showing different content on your website to different people or to Google to try to hide things that might break Google Ads' rules." Google's spam policies for Search (opens in a new tab) (updated August 28, 2026) give a search example: "Showing a page about travel destinations to search engines while showing a page about discount drugs to users."
How does cloaking fool classifiers?
A classifier has to fetch a page to judge it, and the fetch itself carries clues. A 2016 IEEE Symposium on Security and Privacy paper by researchers at Google and North Carolina State University, Cloak of Visibility (opens in a new tab), studied ten cloaking services sold in underground markets and grouped their techniques by the browser, network and contextual cues they read to tell organic visitors from crawlers. It found IP blacklists covering over 50 million addresses tied to the top five search engines and to security crawlers.
| Cue group | What the script checks | How a reviewer varies it |
|---|---|---|
| Browser | User agent string, JavaScript support, mobile or desktop browser | Load the page in a phone browser and a desktop browser, with scripts on |
| Network | IP address ranges of search engines, data centers and security firms; reverse DNS | Load the page from a home or mobile connection as well as an office network |
| Context | Referrer, such as a social or search click, and whether the visitor interacts | Arrive through a link from another site and scroll before judging |
The study sampled 135,577 Google Search and Google Ads URLs keyed on high risk terms, such as luxury products and weight loss supplements, and found that 11.7 percent of the top 100 search results and 4.9 percent of ads cloaked against Google's generic crawler. The most popular techniques it found were detecting JavaScript, blacklisting Googlebot's user agent and IP, and requiring interaction before the real page loads. The figures describe that 2016 sample of high risk terms, not today's open web.
Which page differences are not cloaking?
Pages vary for honest reasons, and a test has to rule those out first. The Cloak of Visibility authors note that split views occur naturally because of personalization, geographic optimization and responsive design. Google Ads says it is okay to show different languages, special offers, location adjustments or versions for slower connections, "but the promoted product or service needs to be the same for everyone." Google Search does not treat a paywall as cloaking if Google can see the full content behind it just as an authorized reader can, and the publisher follows its flexible sampling guidance.
| Difference seen | Likely explanation | When it becomes a finding |
|---|---|---|
| Narrower layout and fewer columns on a phone | Responsive design | The phone page covers a different topic or carries far more ads |
| French text in Quebec, English elsewhere | Language or location targeting | The content behind the translation changes |
| Article cut off after two paragraphs | Paywall or metering | The crawler sees a full article while every person sees an offer page |
| Different ad creatives on each load | Normal auction variety | The number of slots or refresh rate changes with the entry path |
| New page after a click on a sponsored link | Campaign landing page | The landing page is not reachable or matching on a direct visit |
How can a buyer test for cloaking?
The method from the research applies at a planner's desk: fetch the same URL under different profiles and compare. Google's AdSense related search policies (opens in a new tab) set a useful bar for one case, requiring that a page reached through a paid traffic source be "substantially the same" as the page an organic visitor sees. A buyer can apply that bar to any candidate.
A cloaking check on one candidate site
- Pick three article URLs. Choose pages that appear in sponsored links or social posts, since a cloaking script can read the referrer and change the version for that entry path.
- Load each on a desktop with a direct visit. Save a full page screenshot and note the topic, slot count and any pop-ups.
- Load each on a phone over mobile data. Arrive by tapping a link from another site or social post rather than typing the URL, and scroll to the end.
- Repeat on a second day. Some scripts rotate versions or wait for a return visit, so one load can miss the switch.
- Compare the sets. Look for a different topic, a different template, more slots, extra redirects or a page that only appears after interaction.
- Write down every condition. Device, network, entry link, date and time belong with the screenshots, so another person can repeat the test.
One caution from a second paper, Duan, Wang and Lee (opens in a new tab) (arXiv, 2017): detection by repeatedly clicking paid search ads can itself create click fraud. A buyer should reach pages through organic links, social posts or copied URLs, not by clicking ads in volume.
Is cloaking ad fraud?
Cloaking is deception aimed at a review system, which is why platforms treat it severely. Google Ads calls circumventing systems violations egregious, says accounts are suspended "upon detection and without prior warning," and says the advertiser will not be allowed to advertise with Google Ads again. Google's Authorized Buyers disapproval reasons (opens in a new tab) list cloaking, use of dynamic DNS to switch page or ad content, and manipulating ad text to bypass automated checks as circumventing systems practices.
Whether a cloaked impression counts as invalid traffic is a separate question. The visitor may be a real person, so filters that remove bots and data center traffic may count the impression as valid. That is the risk for a buyer: the scan says the page is clean, the traffic report says the visitor is human, and the ad still appeared on a page nobody reviewed. Our guide to types of ad fraud covers the schemes that fake the visitor or the site itself.
What should happen to a site caught cloaking?
Signals such as ad density or templated design call for judgment, because legitimate publishers can show them too. Confirmed cloaking is different: it shows intent to hide the page from review. Exclude the whole domain from every client's lists, keep the screenshots and conditions, and tell the sales contact at the exchange that sold it. Google Ads lets advertisers exclude placements (opens in a new tab) by domain, and Google's Search Quality User report (opens in a new tab) has a "Cloaking and sneaky redirects" category for pages that present different content to Googlebot and humans with abusive intent.
One exception deserves a call before an exclusion is final. Google's spam policies note that hackers can use cloaking to make a hack harder for the site owner to detect. If a long running local publisher suddenly shows a cloaked page, tell the publisher; it may be the victim. Keep the domain off plans until the publisher confirms the cleanup and a fresh test passes.
Before closing a cloaking case
- Benign explanations such as layout, language, location and paywalls have been ruled out.
- At least two people saw the difference under the recorded conditions.
- The domain is excluded on every active list and deal, not only the current brief.
- The exchange's sales contact has the evidence and the date.
- The case and its evidence are in the domain's record, with a date for any retest.
What does a cloaking review look like on a real brief?
Fictional example
A specialty food plan in Maryland and Delaware
A fictional group of olive oil and vinegar tasting shops in Baltimore, Annapolis and Wilmington wants display beside cooking, recipes and food culture content. One recipe site on the shortlist has a clean scan report, strong topic fit and three ad slots per article on a desktop visit.
On a phone over mobile data, arriving from a social post, the same article opens as a twenty page slideshow with ads on every slide and a pop-up offer for diet supplements. A direct visit on the same phone shows the three slot article again. A second planner repeats the test the next day and records the same split.
The planner excludes the domain on every client list, saves the screenshots with device, network and entry link, and sends them to the exchange's sales contact. The other recipe sites on the shortlist go through the same two view test before the plan is approved.
How does PlacementGraph view a site the way visitors do?
Frequently asked questions
Is serving a mobile version of a page cloaking?
No. Responsive layouts and separate mobile pages change presentation for small screens, and the Cloak of Visibility authors treat optimized content for small screens or local visitors as benign. It becomes cloaking when the phone version carries a different topic, a different product or a heavier ad setup hidden from reviewers.
Can an advertiser's landing page be cloaked?
Yes. Google Ads lists showing Google a compliant landing page while showing people different content as cloaking, for example showing clothing to Google when the site sells guns. That is the platform's concern with advertisers; a media buyer's concern is the same trick played by publishers on the sites in a plan.
Does a verification report rule out cloaking?
No. A report reflects what its crawler or tag observed. A cloaking script built to recognize crawlers and data center networks can show them a clean page, so a clean report and a cloaked site can coexist. A manual test under visitor conditions is the check that adds evidence.
Why do some cloaked pages wait for scrolling or a click?
Interaction is a cue that a real person is present. The 2016 Cloak of Visibility study found that requiring visitors to interact before delivering the real page was among the most popular techniques in its sample, which is why a buyer's test should include scrolling and tapping, not only a page load.
Sources
- Circumventing systems (opens in a new tab)Google Advertising Policies Help
- Spam policies for Google web search (opens in a new tab)Google Search Central, updated August 28, 2026
- Cloak of Visibility: Detecting When Machines Browse A Different Web (opens in a new tab)Invernizzi, Thomas, Kapravelos, Comanescu, Picod and Bursztein, IEEE Symposium on Security and Privacy, 2016
- Cloaker Catcher: A Client-based Cloaking Detection System (opens in a new tab)Ruian Duan, Weiren Wang and Wenke Lee, arXiv, October 2017
- AdSense for Search Product-Integrated Feature policies (opens in a new tab)Google AdSense Help
- Common ad disapproval reasons (opens in a new tab)Google Authorized Buyers Help
- Search Quality User report (opens in a new tab)Google Search Console Help
- Exclude specific webpages and videos (opens in a new tab)Google Ads Help
Researched and written by PlacementGraph Research. Read how we research, source and update these pages. Corrections: diana@placementgraph.com.