Evaluate how he acts after making mistakes. Determine whether he blames others, the situation or if he takes responsibility for his own actions. Your man doesn't have to be perfect, but he may be a loser if he cannot own up to his mistakes.
Suggest trying something new, such as climbing a rock wall or going to a poetry reading. Winners tend to be more open to trying new things.
Talk about his life goals and how he wants to grow as a person. If he doesn't have substantial plans for growth, decide whether that's acceptable to you.
Think about how she acts when you plan activities without her. If she seems to feel threatened, it may be a sign of a personality flaw that will continue throughout the relationship.
Ask yourself if he habitual liar. If he does tell a lot of lies, you can assume the truth doesn't make him look like a winner.
Look at how other people react to her. If she doesn't have many friends or a number of people dislike her, there is probably a good reason, and she is probably not a winner.
Look at how he acts in public when an attractive female is around. If he comments on her appearance or openly gawks at her, he may be a loser.
Keep expectations realistic and don't expect her to change. If she's giving off a strong loser vibe and you don't want to date a loser, cut her loose.