I've never made a penny on Adsense, and probably never will. I think the ads usually look like warts on a site, and if you need to have them on your site then you have other, more serious problems. Unless maybe you're an open-source developer site or something. I think the argument that they are 'zero work' and 'free money' is ludicrous. I'm not against advertisements, in general, but I think Adsense often makes sites look like crappy, low-rent. low-content, spammy, rip-off sites. (And, yes, I'm aware of all the major media companies that use Adsense on their sites.) Another major reason I hate this type of near random text ad is that you rarely have 100% control over what is being presented to your audience...and I'm very picky about who I want to be associated with - even at the subconscious level.
Most importantly, every single time we have tested having Adsense or their ilk on one of our sites, it has lowered our overall conversions. Paying customers are worth more than the pittance you usually make from blind text ads, so we try not to make our customers feel like they should take a shower after visiting our sites.