My impression back when Google really took off was that other search engines were basing their relevance scores on page content and getting lots of spam in thei

My impression back when Google really took off was that other search engines were basing their relevance scores on page content and getting lots of spam in their results from pages that gamed the relevance algorithm. Then here comes Google using human judgment via PageRank and getting great results, because who would link to garbage? Of course the web has changed since then. And I think you're right on in thinking that the signal-to-noise ratio of links has gone way down. But it may not be fair to chastise Google for not getting good results just from page content. Has anyone ever done a good job of information retrieval in an adversarial environment without leaning on human judgment?