scottsonline - 4:11 am on Dec 7, 2013 (gmt 0)
Amazon product ads rank first for tens of thousand of products. Would smack of collusion otherwise. One has paid ads dominating 70% of the screen and "free" results that are paid ads on the affiliate/amazon site.
This page rank update the most blatant link buyers. There was a direct change in qualifying traffick around the time of this update. I think the algo updates are now a monster they barely understand. They minimize the impact.
The bottom line is blatant paid links are still number one. Everything else about quality content and user experience is nonsense. Have the highest ranking back links and you'll rank highly.