The issue is really with speed of judgement. It's all too easy to become close minded after judging something, especially when judging something negatively. The key is remaining open minded as long as possible to take in more information, then you're in a better place to judge. Disagreement in a respectful manner is a reflection of how you've balanced the positive and negative, if you prejudge Internet commenters you'll have made it much harder on yourself to find that balance.