I've waffled on Avatar myself. It's the motherload of all freebies, but when I see it in someone's Achievement list, I know there's only one reason why they played it. It feels cheap, but I don't blame them. OTOH Guitar Hero 3 was so insanely stingy with its 'cheevs that I eventually determined to never play it again, so on my last run I glitched a handful of Achievements, finally bringing me to 215 out of 1000. I also cheated "Day Tripper" because I was about to finish 26 hours after starting Beatles' Story mode.
The Fallout 3 "karma" ones are not only cheesy, but I think a bit harmful to the player's ability to experience the game as they like. I just want to play as a good guy, but if I spend a few minutes prior to leveling up at 8 and 15 or whatever, just wandering around and killing folks because I want the Achievement without replaying the whole game, it lodges a sense of inconsistency in that world.