There are different kinds of trolls. The ones who are obvious are not a problem.
The unobvious ones can be made obvious if you spend about 3 seconds in pause.
Imagine you are on a Star Trek discussion, could be anywhere, let’s say Facebook. Someone asks you; “What is your favourite episode?”
If you and the person were in discussion before about this and that and the other; okay. If the question comes from someone you never recall communicating with, take the pause.
You can post your favourite if you want, and if the response is ‘Why?’ this is a person looking to be annoying. So don’t answer.
Think of it like this; when someone asks you a question out of nowhere, why?
Would you walk up to a person you don’t know and ask this question?
If you’d been sitting there, talking about Star Trek with the person for the last few minutes, it’s a reasonable question. But to pop up and ask, without saying; “My favourite epi is…. what is yours?” means this is a troll.
Use this pattern for everything.