Am I evil?

Sometimes I get into an online discussion with someone on another blog, and the person will assert a point, without any quantitative or qualitative supporting data. My normal tack is to demand that they offer some evidence to support their assertion, which usually results in irritation and annoyance (e.g., "I don't have an infinite amount of time to look stuff up, what do you think I am, a nerd?"). But sometimes I follow another tack, I just plainly contradict what the individual asserted without any evidence from my own end, and simply say "my impression is contrary to your impression." And strangely, I don't experience the same abuse or anger in these cases. Quite often I am on the receiving end of a shrug, and the response follows the form "Well, I guess we agree to disagree, you have your opinion and I have mine, and so be it...." Sometimes, I get bored, and I simply make shit up, stuff I know is incorrect, but the response is still the same, "Well, you have your opinion and I have mine."