As a player, I've never really had a problem playing with/against girls, but I have noticed that the few I've seen do tend to be romantically involved with male gamers, though some played before said romantic involvement. I even got and ex into WHFB at one point (even bought her a Wood Elf battalion, which turned out to be a massive waste, but thats a whole other story). Don't know if she's still into it or not, as the local GW shut down soon after we broke up, but she was interested, at least.
One thing I've noticed about female gamers is that they tend to put a slightly heavier emphasis on the painting aspect of the hobby, for whatever reason. This is not to say they don't play the game, or that they aren't very good at the game, (I've had my *** handed to me by a girl many times in the past), just that I notice female gamers tend field a much greater percentage of fully painted armies than male gamers, and often to a better quality as well. If you ask me, thats one of the keys to getting girls into the game, to approach it from the more artistic aspect of painting and modelling first, as is at least more gender neutral than "IN THE GRIM DARKNESS OF THE FAR FUTURE, THERE IS ONLY WAR!"
However, I do think there is a more passive way that girls tend to put down gamers than flat out attacking their significant others for playing, which then increases the male gamer's discomfort and disrespect toward them: stereotyping. Case in point, the old GW in this area used to be located in a fairly busy mall, so there were often packs of ditzy, "popular" teenage girls roving the mall and passing by. Every once in a while, one of these groups would enter the GW on a lark, look around at everything, take up all the Redshirt's time and attention with incesseant and stupid questions ("So are the Eel-dare supposed to be, like, pixies or something? *giggle*"), pick up every box on the wall and put half of them down in the wrong place, then walk out, giggling to themselves at how "nerdy" that store was, and go over to Claires or some other clothing store. Meanwhile, everybody in the store, female gamers included, are sitting around feeling uncomfortable. Games stopped, painting was impossible with that kind of inncesant noise, and no one could actually buy anything because the redshirt on duty had to attend to the ditzes for 10 minutes. It goes without saying that several deragotry comments would be made about the girls, their intelligence, and their sexual promescuity by the more immature customers in the GW, and then for about an hour everyone would feel really awkward and stupid. It's not the fact that girls were in the store, its the fact that the girls only came into the store to laugh at us. I am by no means implying that all girls who enter a GW are like this, but for us, it was a large enough percentage to detrimentally effect many of the regular's opinions of teenage girls in the store, and so many of them tried ot discourage any girls who walked into the store at all. Even when a new female player actually bought something, many of the regulars were unnconvinced that this was not an elaborate joke, that the girl wouldn't just come in one day with a bunch of pink-dipped Eldar or High Elves, play one game, then smash them on the floor, laugh, then run outside and merge into the nearest pack of ditzes.
In short, it's not the female gamers who giver male gamers bad opinions of girls, since they tend to be very cool and often smarter than many of the guys, but instead it's the kind of materialistic chick who snickers when you walk by carrying an army case that really hurts, which then makes the male gamers less receptive to females in general.
(Also, props to Eldargal for breaking that creep's nose. You hit anyone over a game, much less a girl, you deserve much worse than that)