I find myself making negative comments more than I would like. But these happen to be about points that are the most interesting to discuss. The resulting discussion is very useful. What am I to say about things I like? +1 adds nothing to a discussion.
There's a way of criticizing that still honors—or at least doesn't trample—the creative spirit in the work being criticized. That's what we're going for here. Substantive criticism is helpful because it adds information. Snarky dismissals merely puff up the criticizer. As long as that's not your intent, your comments are likely to be fine.
