Why would women go out with guys who dress and behave like slobs?

I was at a nice restaurant the other night. Sitting at a nearby table were three couples in their late 20’s to early 30’s. From the rings, I could see one couple was married.
The women were all dressed up: nice hair, makeup, neat clothes, shoes. However, the guys were slobs: jeans, sneakers, one had a t-shirt, one of the brain surgeons was even wearing a ball cap backwards.
Why would any woman date a guy a second time if that is how he behaves in public? Why bother spending the time and money getting all foxed up if the guy is a slob and does not show similar respect to you? Do you think you will change him? Are there no nice guys out there who are willing to dress up a little bit when going out to dinner?