;) Google decided that companies that pay them more (between price per click and CPM) are more relevant? Color me surprised. Google is also on a jihad against extremely useful sites that do things like price comparison and reviews. Guess why?
There's a lot more to it than that. If somebody clicks your ad and then peel out within a few seconds then obviously your ad didn't do anything for them so the next time somebody clicks, your price goes up. Pretty soon you write a better ad. I know it isn't popular to say this but sometimes when I'm looking for a product to buy, ads are relevant. And the better the ad the more I appreciate it.