Well this isn’t always an easy thing to do, depending on the skill and charm of the subject. But womanizer’s usually are not interested in long term relationships, so any behavior that is the opposite of that, should send up a red flag. Some experts say the following; they are unavailable by phone or in person a lot of the time, maybe on their cell phone a lot with personal calls, and they might even say provocative things to you rather early in your friendship. Of course these are just a few examples. But if you have a hunch, 9 times out of 10 our hunches are right.