Google is warning webmasters about the perils of utilizing redirects that Google views as manipulative with the intent of deceiving searchers. This type of redirect is also well-known as cloaking, although the term "sneaky redirect" is a better description, especially for newer webmasters who might not know the cloaking terminology.
However, some redirects deceive search engines or display content to human users that is different than that made available to crawlers. It's a violation of Google Webmaster Guidelines to redirect a user to a different page with the intent to display content other than what was made available to the search engine crawler. When a redirect is implemented in this way, a search engine might index the original page rather than follow the redirect, while users are taken to the redirect target. Like cloaking, this practice is deceptive because it attempts to display different content to users and to Googlebot, and can take a visitor somewhere other than where they expected to go.
It's been a common trick for spammers, especially in years gone by, to serve up one version of the page for Googlebot and another version of the page to users, whether they are providing better content to Googlebot, or serving a page that is completely different – right down to a completely different topic – to users.
While Google has been able to catch bait-and-switch redirects for quite some time, it appears they are also cracking down on webmasters who are serving different pages based on things like one page to desktop users and another completely different one to mobile users.
Some examples of sneaky redirects include:
- Search engines shown one type of content while users are redirected to something significantly different.
- Desktop users receive a normal page, while mobile users are redirected to a completely different spam domain.
Google is also warning about hacked sites that might redirect users to other pages or sites, specifically citing examples where the user coming from a Google search gets redirected while someone to goes to the site directly, such as through a bookmark or by typing the address into the address bar, goes to the proper site or page. Or hackers base it upon things like particular user agent, referral, or device.