I once read a definition of troll that said that troll is only really a troll if they are not reognised as being one. The act of trolling involves going unnoticed, flying under the radar. Once you label someone a troll, they are no longer a troll, even if they were before. They might be a troublemaking asshole, but not a troll.

It's like if you tell someone a secret, it's no longer a secret. Or if you notice something you hadn't noticed before. It's no longer unnoticed. Or it's like answering "No" to the question "Can you hear me?"

A troll who gets spotted as being a troll has failed at being a troll.