There are 3 types of trolls: The fun troll, the dumb troll, and the natural troll.
1. The Fun Troll
The fun troll just wants to mess around and f with your mind. There's nothing malicious about this brand of trolling. Unless you're Joe Pesci, you'll have a nice laugh at the end of the troll session. It's all in good fun.
2. The Dumb Troll
The dumb troll is a troll who persistently makes outrageous comments not because he's trying to be disingenuous, it's because he's too much of an idiot to realize that he has been duped. These are the types who stubbornly refuse to change their mind and regurgitate untruths. Feel pity for these trolls and move on.
3. The Natural Troll
The Natural Troll is a troll who is not trying to troll at all, it's just how he is. It takes a special kind of asshole to be constantly trolling every part of the day, but he's not trolling--he's just living. It might be best for your health to avoid Natural Trolls at all costs.
Everybody trolls. It's all a matter of what kind you are. As with all things in life, moderation is the best policy. Too much trolling and you'll find yourself stuck on an island with giant blood-thirsty crabs who love the taste of troll. Consider yourself warned.