I don't bother with online achievements at all unless it's really straightforward like "play 10 matches" or I can boost it fairly easily. In fact, games having online achievements can make me decide not to get a game (if I'm only a little interested) or change which platform I get it for (for some reason I don't care nearly as much about PS3 trophies as 360 achievements, and I don't care at all about Steam achievements).