Actually, the only value I generally derive from visible karma is that I can then sort the comments by karma (which I do). Seeing user karma is only useful if I want to see whether other people also assume they're a troll, and their recent history usually does the job for me just as well...

Maybe we should remove, or at least hide, karma, instead of highlighting it? Why do we show user karma and even have a "Top Contributors" list like this...?