The most discerning statement that I've read in the entire Adsense+Earnings dialogue is one I attribute to EFV. Essentially, he stated that Adsense and affiliate ads are a natural adjunct - ergo a "successful companion and addition" - to websites that labor to help people decide how to (wisey) spend their money.
I remember that post as well, and it's one I have kept in mind...not just for adsense, but for other sites that I want to sell advertising space on.
I didn't think that way when I originally created my site(s), but it was just something that came naturally.
Once you fully grasp that idea though, it makes it much easier to monetize a website (and realize why some websites are MUCH harder to monetize than others).