I think that the reason that girls are afraid to say that they're girl gamers is because of the backlash they'll get. I had a second account on Halo 2 a long time ago called GunslingerGirl and I ended up canceling it because of the way people reacted to the name. On one hand you have the stalker type guys that will ask you personal questions and treat you like some kind of god, which I don't want. On the other hand, there were numerous times that I would go into a match and people would say "Oh boy, we have a girl on our team, everyone quit because we're going to lose." I couldn't understand that because I clearly had the highest rank on the team. Another great example of this is when I was playing TF2 on my previous PMS tag and, while I was leading in points and carrying the team, one of the guys made a snide remake about how it's expected that I'm not good because I'm a girl. I didn't really get that one because I was doing the best on the team but it's annoying that, despite how I'm doing, because I'm a girl, it's immediately assumed I'm trash or something. -_-
It's because of that kind of crap that girls don't want to admit that they play. It's one of the reasons I don't play in public rooms often and, if I do, I don't have a mic on (people in public rooms aren't that good and complain a lot too lol).
As for other females, I don't have any problems with them unless they're only playing to flirt. I hate when I get into a room on a game to see that a girl is simply there to flirt with all the guys. They end up making all girl gamers look bad and it's extremely irritating. I'm fine if there are girls that want to play or stuff like that, but when they're just sitting there flirting because they think they're special or something, it really annoys me. It also bugs me when they're are girls in the competative scene that aren't trying to get better or anything but just do it for the attention.
As long as they aren't playing for the attention they get, I love playing with other girls. That's why I joined PMS a long time ago- because I wanted to play with more girl gamers. ^_^