Theoretically, they could do a lot of things, but plenty of those would get them in hot water from a regulatory standpoint. Also, don't underestimate the adver

Theoretically, they could do a lot of things, but plenty of those would get them in hot water from a regulatory standpoint. Also, don't underestimate the adversaries. Ranking well on Google means earning a lot of money. So much so, that I'd argue the SEO-people are making significantly more money than Google loses by having spammy SERPs. They will happily throw money at the problem and work around the filters. I don't think you can really select for quality by statistical measures. Google tried and massively threw "trust" at traditional media companies and "brands". The SEO-people responded by simply paying the media companies to host their content, and now they rank top 3, pay less than they did by buying links previously, and never get penalties.