Probably the ads. For a while, Google helped made this even worse by paying companies like Dell to set the default search on new PCs to specially-customised version of Google with far more prominent ads that were less clearly distinguished from normal search results.
Dell has been installing crap since at least 2006/07. Thats when I started wondering why all new PCs at a certain company where all infected just few days after purchase. Then I realized this thing (myway?) was being installed by default.
I really didn't think it was ever a Google product though. Correct me if I'm wrong.
Ads may distort this for some users, though...