Online forums - do people think you're a troll?

I've been banned from a few forums in my lifetime (Mumsnet, for example). 

Every time has shocked and upset me.

People assume I'm a troll and I'm left with that familiar feeling: "I don't understand what I've done wrong; am I living in a parallel universe to everyone else?"

The rejection stings and baffles me.

Does this happen to anyone else?