A Yahoo Answer trolls is usually someone who enjoys to annoy everyone else on Yahoo Answers (but some aren't like that). The Yahoo Answers Trolls are usually found in the Polls & Surveys category but they sometimes venture into other categories. But there are many types of Yahoo Answers Trolls.
The Scroll Troll: A troll who loves to create an incredibly long answer so you cannot see the other answers without scrolling down the screen for at least 5 minutes. The smart thing to do when you see a scroll troll is to thumb them down.
The Reporter Trolls: Reports innocent questions and answers that are not angianst the community guidelines just for fun.
Spam Troll: A troll who always asks the same question or always answers with the same answer.
Funny Trolls: Trolls that make the Yahoo Answers users laugh. Unlike the other trolls, these trolls are actually liked by most of the Yahoo users.