Since I’ve been asked this a number of times, I believe there are two types that girls should avoid.
First of all, don't ever date a guy who wears shorts. A terrible mistake. He might look all right, he might smell nice, he might have a million attractive features, but ultimately he will turn your life into hell (worse – boring hell), and you will regret your choice for the rest of your days. Shorts are not the sort of thing that a man should wear. Unless he is playing football, in which case the logical question would be: “Why on Earth…?”
Secondly, don't ever date a guy whose favourite band is Joy Division. Nothing against Ian Curtis or Manchester, and it’s okay if the person you date likes “Decades” or even “Atrocity Exhibition”, but saying they are your favourite band is, I believe, a direct threat to your well-being. Anyone’s well-being really. You don’t want to end up swallowing Prozac for a living. Besides, who will think about the children?..
Now. If we are serious about this for a second, let me put it this way: find someone who knows what you want, not what you need. Rest will take care of itself.