indyank - 5:28 pm on Nov 2, 2011 (gmt 0)
"For our algorithms, ads generally don't play a big role."--John Mueller, Google (http://www.seroundtable.com/ads-google-algorithms-13110.html)
But ads do play a role. We never know what he meant by "big" but ads do see a mention at several places in their latest quality raters' guideline. The guideline isn't very clear on when should the presence of ads be treated as indicative of spam. But its usage at several places would have a strong influence on the rater's judgement.