From my readings around here these negative comments are most often attributed at developments that partially aim at creating controversy. If someone starts a Twitter clone country club or runs away from Diaspora to start a meme blog it seems save to assume that this is going to result in some form of dissonance. I personally find the "Ask HN" section extremely civil never really saw someone tearing down a project. Most backslashes seem to appear if a project promises more than it can deliver. The community seems fortunately resistant against too obvious forms of hype.