1. He treats you like one of the guys. If he's making explicit comments or telling raunchy jokes, he could be testing whether you're willing to connect on a sexual level. Thus, he may not plan on working to reach boyfriend status.
2. He's charming...repeatedly. A guy who retells anecdotes or gives you the same compliments as he did on your last date could be on autopilot. That connection you thought you made may be an act he uses to get chicks into bed.
3. You don’t bond in person. Electronic communication is a way of life, but a man who's looking to date will call you and go for meaningful conversations face-to-face, too.
4. You usually stay in. Chilling on the couch may seem sweet, but be suspicious if he's not taking you out. Being seen with you could ward off other women, so if you two don't socialize in public, it may be that he doesn't want to be seen as taken.
Sources: Psychologist William July PHD, author of Confessions of an Ex-Bachelor; Sexologist Logan Levkoff, author of Third Base Aint What It Used To Be