When I took Kung-Fu, it wasn't at all rare to spar women in class. Any reservations I had about fighting a woman that was out to do me harm was beaten out of me in that class.

I'm not condoning hitting women, and I'm not trying to be shocking or a jerk, but if someone is out to do me harm they will be stopped if I can manage it.

All of the same critical strike points apply to a woman except for perhaps the crotch shot and I wouldn't rely on a crotch shot with a man either.

The only time I would consider "fighting dirty" to mean anything at all is in sanctioned fighting events where there are clear rules as to what is acceptable. The term means nothing in a survival situation.