Dags90 said:
My guess would be a sort of Green Beard Effect [http://en.wikipedia.org/wiki/Green_beard].
It helps some gay men recognize each other. It's hanky code, but with less paisley.
Holy crap Dags, I just nearly choked to death on my coffee laughing at that ;-)
Thing with stereotypes is that there is often a degree of truth to them. Sometimes those stereotypes are deliberately affected, sometimes they just happen.
I didn't wake up one day and decide to be butch, it just happened organically. But a lot, probably the overwhelming majority, of gay women aren't butch. Some gay guys flame a little harder than others - sometimes on purpose, sometimes not. The reasons for why that happens would fill a book and there is probably no legitimate conclusion that can be made.