Good question, but has to be answered with another question. What appearance?
Most of the time the trolls we deal with are anonymous. Whether they're male or female is just a figment of our imaginations either because we have to guess or after they've said so. But even after they show themselves we still don't know for a fact.
For some reason while dealing with a troll here named skeptic I pictured the account holder as a girl. A very young one. I'm not sure if it was the language she used or didn't use but I'm still unable to picture the person behind the account as male.
I think it's possible that we are programmed to picture everybody we read as male until something indicates otherwise. Even in stories women are always described more visually and sensually than men, there is always an indication that the character is female but indicating that the character is male has been deemed unnecessary, since the men are the protagonists of the world.
2 of the worst trolls on this site are definitely male.
The way I see it, if you're not being trolled, you're not being real.
If you can take a trolling you're strong enough to take on anyone!
Trolls playing the victim is funny.