undercover wolves

Matthew 7:15
beware of false prophets, who come to you in sheep's clothing but inwardly are ravenous wolves.

To beware of false prophets is a common warning in the bible but are we actually doing it? It seems like we are aware of the possibility of false prophets in theory but don't really expect to encounter them, even though the bible says that it's almost certain that we will. To beware is to be on the look out for them - it's not a witch hunt but it does mean that we try to evaluate  what people are saying.
These wolves look like sheep. If they looked like wolves there wouldn't be much of a problem. If they came along teaching crazy stuff it wouldn't be much of a problem because we'd probably notice. The danger is that they will seem plausible, they will seem attractive, what they are saying will sound like something that we want to be true. Jesus pulls no punches, they are ravenous wolves and we are in danger.

How should we go about this, the Bereans in Acts 17:11 give a good example:
Now the Berean Jews were of more noble character than those in Thessalonica, for they received the message with great eagerness and examined the Scriptures every day to see if what Paul said was true.

They weren't accusing everyone of being a false prophet - they listened to the message with eagerness. But they weren't just taking Paul's word for it - they examined the scriptures every day to see if he was telling the truth