A recently granted patent named ranking documents can be looked at as if it was a Penguin patent or maybe a patent on how to trick SEOs into thinking their pages are ranking or maybe both.
In short, the patent discusses finding spam such as keyword stuffing, invisible text, tiny text, page redirects, meta tags stuffing, and link-based manipulation.
It also discusses how to fake the search rankings without changing the search rankings. Tedster explained:
Rather than allow the rankings to respond immediately and directly to those changes, the patent explains a system that would change rankings in unexpected, counter-intuitive ways - while the rankings change from a first position through transition positions and to the final "target rank" position. In other words, significant changes in position continue to happen even though there is no change in page's ranking factors!
How does Google do this? Bill says a time-based delay response, a negative response, a random response, and/or an unexpected response.
There have been a lot ranking changes that are unexpected and hard to explain, maybe this is related?
Pretty interesting stuff!
Forum discussion at WebmasterWorld.
Image credit to ShutterStock