I have a question--why does it tend to be women who are accused of being fake geeks, and not men?
Well, okay, it's because geekdom has historically been a male-dominated field, but you could say that about ... well, an awful lot of fields. Sewing, now, that is historically a woman's craft, so you'd think you'd see more men in costume derided as fakes who had to get their wives or girlfriends to sew for them, not real costumers, right? No? (I kid, I kid. If someone wants to wear a costume but not make it, that's perfectly fine.)
I think anyone should be able to wear what they want at a con, show as much skin as they like. The double standard I see is that men in costume are more likely to get attention based on the quality of their work, regardless of how hot they are, while women are more likely to get attention based on their sexiness. But I think this is changing. 'Course, I do a lot of costumes based on books, which means I get ignored regardless

Now, I'm not a gamer--just, never been interested in games, not my thing--but there are a few video/computer game characters I'd consider dressing as, simply because they look awesome. But I wouldn't actually make them without reading up on the character, maybe reading any tie-in novels if there are any. Probably some people would think I'm less of a geek for not playing the game, but that's their business.
(neoakaj--what do you mean by one Slave Leia who was genuine? Surely everyone knows who Leia is?)