Sure. They exist. Usually they can easily be recognised by the fact that they look more the way a man would like a woman to look than how a woman would like herself to look. Look for skimpy attire and exaggerated attributes. Some of them you won't believe until you see them... [Someone posted a message about buttons on the FurryMuck park board a while back; one of his example buttons said something like "I've got big boobs and a miniskirt, guess what my player's RL gender is!"]
As for crossmuckers in general... I read an article (in a Norwegian paper)
about the net recently, in which the author mentions this "new"
kind of roleplaying and concludes that roleplaying in general and cross...
make that the gender game (mucking was not specially mentioned) in
particular can be considered a new art form. So (as I said to a
crossmucking friend of mine) we're not perverts, but artists! [Hmmmm,
wonder if I can get a grant...?