So many comments agreeing with this earnestly without a trace of irony. I wouldn't know how to respond but your replies are hilarious.
(This is going to be a bit long and I'm sorry about that, but i think it's a more complex issue)
Anyone can express a fandom or dress up however they want for events, the only time you get to be pissed of at someone is if they actually act inappropriately to unwilling people or cause trouble, otherwise it's not for anyone to make assumptions or judge them. I still do think that fakeness or insincerity exists in fandoms.
Some things are more popular than others and there are things that are considered cool to like, and people, both genders, respond the same way they would with any other trend. So people pretending to like or know about something more than they do is a thing that happens, why wouldn't it. And that sometimes leads to people misrepresenting a property out of ignorance, and i think that deserves to be called on out like anything else that's dishonest. For people like personalities and media commentators who need to market themselves and be in touch with what's popular, i understand acknowledging and talking about them and that's fine, but if they pretend to be a bigger fan of something they're not it's bs.
But that's not to say it's for anyone to decide who's allowed to like what. No one, no matter how much you love something, has ownership of a fandom and gets to set standards of who's worthy of enjoying it. Even people who like something casually or maybe they just like specific aspects like the character design can express their love of it, including cosplay. If they're honest about it it's not for anyone to judge. I love and support this movement of women being no less capable of loving geek things, but to say insincerity (and both genders have it) is completely non-existant is untrue.