I've never had the problem with people pretending on freenode, not like you do on, say, yahoo chat.
Seriously, do we need to promote the stereotype of "don't believe someone if they say they are a girl". Better advice, say "cool" when someone says they are a girl, and otherwise ignore it.
In a sort of case/point, the most famous female on freenode, imho, is Christel http://blog.simplychristel.net/ the person that took over for lilo (when he passed away) on freenode, not including the other FOSS projects she's involved with.
I don't think I would insult her (and myself) by suggesting she isn't female, nor would I insult her (and myself) by 'throwing' myself at her.
She (and any other woman) should be respected, by the same standards you would respect a male.