I think talk about ads as a primary rankings factor of your Panda score is a complete waste of time.
A secondary factor, yes. I.e a page plastered with ads *could* put off visitors, which *could* increase bounce rates and other user metrics.
That's why talking specifics is a waste of time. User metrics are probably measured at each keyword/phrase level - and each keyword may result in users favouring different things.
This is a completely dynamic and changing game, in my opinion. Also meaning that what is relevant today might not be tomorrow.
That's my opinion, anyway.