Are they married? Avoid
Are they recently separated? Avoid
Do they talk about their ex? On the first date, definately an avoid!
Did they decide, without asking you, what to do on the first date, where and what time? Be cautious. Definately potential for control freakyness. If they they choose your drink/meal for you then definately avoid!!
Does he ask questions,and listen to your replies? Good sign! If he follows up on your answer with a supplemental question, even better!!