My feeling is a troll is a comment designed to provoke a knee-jerk emotional response, usually defending yourself, someone or someTHING else. It's not any argument or debate, although those things may contain some elements of trolling such as generalizations, spurious logic and personal attacks.

Nice troll, Peter.

Personally, if I can find sense in something, I'll respond. If I find myself getting upset, or find that I'm arguing with someone who doesn't believe in logic, I won't.