If you hear someone preaching (or teaching) about himself or herself - or about their own ideas, beware. Whenever a preacher or religious teacher is teaching about anything other than Christ or biblical truths (which you can find in the Bible) - he or she is probably a false teacher at that time. This is true even if they sometimes preach otherwise.
So there's the human dilemma: false teachers usually aren't always false teachers. Sometimes they preach the truth. Sometimes they preach what's biblical. Our human mind wants to label someone a false teacher and then never listen to them. God never said not to listen to false teachers though. He just said to test everything that we're taught (against His Word). And He said for the false teachers to repent.
So who will confront the false teachers --- and then still have the ability to listen to them?