foobeans - 11:42 pm on Oct 27, 2011 (gmt 0)

There's a good video about this correlation (amount of ads and lower ranking) - search G for "negative ranking factors" and watch the video (adsense at about the 4 minute mark)

it's called the back button effect which in turn contributes to high bounce rates which in turn affects your overall rankings not to mention quality scores

I agree - probably more to do with people hitting the back button than the ads.