not true.
Adsence uses a completely different algorithum than the search bot, and so does Adwords with their quality score ranking to your page (uh oh, just spilled some beans
)
Im not an adsence pro (adwords maybe) but to get a certain type of ads to show (the ones that you want because they pay the most) use proper html formating, heading tags, alt tags, meta tags and 2-3% kw density