Why girls don't last long as vampires?

There is an old joke that the worst suffering for girls is that let them dress very nicely but lock them in a room without mirror.

Well, there's also a legend that says that once you become a vampire, u will be very good looking regardless of man or woman for seduction purpose. Well, also note that vampires don't have reflections on the mirror.

Imagine some girl become very good looking after she was turned into vampire, but she will never last long because she will never see her own reflection.

Well, I think this joke is pretty lame, but hopefully you guys will be entertained.