[TeMPOraL]

I too would like to see an experiment with two types of votes (agree/disagree and quality/shitpost), but I don't think there's a big problem here. Things balance out in the end. Some people instinctively downvote things they disagree with, other upvote posts for quality regardless of their personal position on the topic; some, like you, rescue comments. Things can be in flux initially, but within couple of hours they stabilize, and the outcome is decent enough. The key thing is not treating karma points and "black/grey" instability personally; it's just the mechanism at work.