I would say that yes, over optimization, as you described it, is a problem. Google has said that they use a number of algorithms to detect paid links. It's likely that your paid links won't yield good results, and it's even possible that your site will be penalized for it. Of course you can try to find new ways to game the system, but remember that your adversary is Google itself.
If you want a good search ranking, Google has consistently told us how best to achieve that: "A well-structured and regularly maintained site with original, high-quality content."
EDIT: I should have checked the dates. This thread was well answered over a week ago.