If everybody else is playing always-defect, and you're playing always-cooperate, you're going to get screwed, completely and totally.
I already fell to this logic once: You can't win any tech item of real value on ebay for anything like a decent price if you bid like a normal person. Everybody snipes, so they can win while keeping the price low. I've always considered sniping to be rude, at best, and pushing pretty hard on the bounds of unethical. But, if you ever want to actually get what you're shopping for, you have to snipe too. So I use JBidWatcher. It's nice. It works well. I still feel bad about using it.
What made me think of all this again is Amazon's use of Pepsi Points. I'm glad they didn't do it while I was still there. I am, frankly, disgusted by it. The ads on the gateway were bad enough, but this is just /sad/. I can't explain why, it just is.
But I drink a lot of diet pepsi. A /LOT/ a lot. And I like music. And you can buy mp3s from amazon, with no DRM supposedly, for 5 points each.
It's not the same as the sniping thing. The pepsi points aren't /wrong/, just... I dunno. Disappointing. But given my initial reaction to them, to come back and think, hmm, maybe I should start collecting these things and benefit from it... I dunno.