IMO, it isn't pretense; it's the real person coming out for all to see.
Well, you could be right about that, and in fact, I find this even more scary!

Nationality plays no part in it - jerks are jerks, no matter the language they speak.
Sure, jerks are everywhere, but what I often perceive in German forums is not only a jerk thing, but a matter of a certain mentality, or attitude. Spoke to some friends about this on the phone today (all Germans), and they felt the same way.

Kirsten