Alan Bleiweiss: If a site has "too many" ads, to the point of being painful for visitors to get to the content, that can and sometimes does result in a penalty (research "Above the fold penalty") or a manual action. If the site is not considered of high enough quality or trust, by a manual reviewer for example, that can result in a penalty or manual action.
Steve Gerencser: And remember, the advice of the adsense group is very often opposite of the advice of the search quality group. You have to find a balance between the two that works for you.
Can AdSense ad placement be major reason for search traffic/SEO rank decrease? 
