Yeah karma systems tend not to be a good thing on gaming sites in my experience. It's a cool thing but... things can go sour very easily. Just a random two cents via a few bad experiences.
Just sharing that I had an internet company and I advertised via a few major forums. The karma system was abused by the competitors. I get red nuggets (bad karma) and it made me look bad despite my continual positive reviews. Karma can be given for any reason. It ends up being irrelevant and useless. I'd rather them insert a sort of "itrader" "feedback" system for members to post positive runs ins... but even then it's not that great of an idea lol