I definitely share this experience, for instance in many of the recent "Groupon is a scam" threads, or anything having to do with Android. It becomes a disincen

I definitely share this experience, for instance in many of the recent "Groupon is a scam" threads, or anything having to do with Android. It becomes a disincentive to participate in conversations about certain topics. I think one thing that might help, and that often spurs relatively useless chains of comments, is to clarify exactly when a post should be downvoted. I think some people use downvoting to express disagreement, but since downvoting not only compromises someone's reputation (via karma) but also minimizes the visibility of the comment, the effect is punishment for that disagreement, which again motivates me at least to avoid controversial topics where I seem to hold an uncommon view.