Trolling is a fact of life on these forums. But starting witch hunts reflects poorly on all of us.

Effective trolling will raise an issue that people are genuinely concerned about, in such a way as to provoke a defensive emotional response. If I feel someone is subtly trolling in this way, I find the most effective response is to offer a polite, reasoned argument that addresses the raised concerns. This approach is beneficial to any onlooker who shares those concerns, it avoids playing into the hands of the suspected troll. It also avoids needless accusations, which is especially important if my suspicions are wrong and the person is just raising a genuine concern.