1. He doesn't care about your feelings
If you vocalize that something that he is doing is bothering you or even hurting you- but his response is "whatever", or he sweet talks you but continues the same action. He is definitely an ahole!
2. His goal is to make himself happy
If he continuously puts his own well-being and wishes in front of yours, then he cares more about what he wants than you.
3. He thinks highly of himself and no one else
If his ego is the biggest part of him that he has to offer, don't expect change. He obviously doesn't have respect for anyone...including himself.