I don't understand the fake geek girl thing. I can't say I've ever heard anyone accuse a woman of that personally. Usually they just call her an actual geek.
I've had it happen to me a couple of times in my life, both regarding geeky stuff and sports. I had to "prove" I wasn't a "poser". Though honestly they were more rare occurrences for me. Usually I get met with more appreciation/comradery for being a fan... like Halforums!
It usually gets thrown at cosplayers. I think Kags could probably talk more to that.
This is all just conjecture on my part, but I think it's fallout from the "booth babe" culture of the last couple decades. Used to be companies would hire models (or just pretty girls) to dress in costume and bat eyelashes at the conventiongoers with only a cursory (if that) knowledge of the product/character they portrayed. And, of course, since these pretty ladies were either intimidating to the socially inept, or genuinely out of the league of the nerds, it bred resentment under the surface. Then when these socially stunted Morts encounter a genuine fan of the culture who happens to be female, out comes the misplaced hostility. It's the growing pains of getting past the whole "girls don't like comics and video games" stereotype that most of us grew up with. I don't think it is as common as we're led to believe, but instances of it happening are spotlighted so that everybody hears about it. Which is good, because it's part of stopping the hostility and making it "ok for girls to like this stuff."
Sorry, I'm late to the party!
And this topic has run it's course a bit, but my two cents:
Being called a fake geek is normally relegated to the convention scene in my experience. And now, it generally happens to cosplayers. It happens less to just general con goers now. Much less than it used to anyway. I think people see cosplayers as kind of an uber fan and feel the need to test them - double check their fan status. Which, I don't agree with, I mean, I've considered cosplaying characters I know nothing about. I just liked their costume. But cosplayers are easy targets because we wear our badge clearly, what characters we love.
I think Gas hit the nail on the head with talking about booth babes. And it's still a pretty big thing today. So many companies will hire very attractive women to dress up and sell products, which I think irks a lot of people because they go to the booth, excited to talk about the product/comics/statues/art (and hey, talking nerdy things with a hot girl, sounds kind of exciting) but then are completely let down when she knows nothing.
So, I get the hesitation, but I don't think it makes 'testing' girls necessary. And like I said, it happens more at conventions. I've never been accused of anything when I go to my local comic shop - the guys there are the best! But at cons, I've been asked aggressively about what I'm cosplaying and if I know anything about the character.
I dunno, it's a topic that gets a lot of discussion in the online world, but I kind of don't care so much. I'm going to like what I like regardless if people feel I'm a good enough fan or not.[DOUBLEPOST=1393862618,1393862335][/DOUBLEPOST]Also, there was a comic I saw once that kind of sums up how I feel - how cosplayers spend a lot of time, money, effort on costumes so a lot of us can't afford to keep up wtih comics. I'll see if I can find it..