tristanperry - 1:14 pm on Feb 27, 2011 (gmt 0)
I'm starting to wonder more and more about the ad-to-content ratio. Some of the sites which took the biggest hits (EZA, WiseGeek) have got a fairly large ad-to-content ratio. In-fact I've seen some cases of EZA and WiseGeek pages which have more text in the ads than on the page's content.
But at the same time, I personally think that this update is fairly complex and brings in a massive array of different factors and indicators (which would be consistent with the fact that different sites and different types of sites have been hit, and that Google spent perhaps a year on this update).
I think it might well look at everything from SERP bounce rates (going to a result, coming back soon after to click on other results) and ad-to-content ratios to quality of content and backlink profiles/signals.. and much more. And with a fair few false positives, too.