Several past videos on Google Webmasters have talked about the ranking strategies of Google and how it has evolved with time. Matt Cutts, can be seen getting more into the SERPs in the latest video.
Cutts is addressing to an interesting question: "How can Google be confident with its SERPs, when relying on inherently subjective signals that influence which sites display (i.e. using human 'quality raters' to evaluate entire domains without the context of the search query itself)"?
Answering to the question, Matt Cutts said that a large part of human quality raters take a search and look at it side by side. They don't look side by side without knowing why they are seeing; they actually do see the context of the search query. They look at the domain and the search query and figure out how the two interrelate.
Matt also said that people who think that search engines are completely objective ignore the fact that every search engine has its own set of philosophy, algorithms, and ideas about what the ideal set of search results is. Moreover, there is no ideally scientifically proven best way to rank website.
Google tries to listen to outside feedback to improve search engine rankings. Cutts referred to Panda update explaining that Google actually worked on spotting low quality content that was in-between quality team and spam team. It was the content that was not actually spam but near to spam. Google worked on that for months before it began considering what the larger public was saying.
Matt said that Google is an engineering organization and it is possible for people to be wrong. It is also possible for Google to show not much or too much domain diversity. So, it is important to listen to what people say outside Google and consider their feedback as well.Matt Cutts on How Google Thinks About Search Quality While Replying on the Subjective Signals!,