I was messing around with a girl for a number or months, even a year and the whole time she dead set claimed she was straight, even to me and her other close friends. She's since changed that and no longer gives herself a label. I've got to a point where I'm reasonably happy to call myself bisexual. and I met a lovely girl the other day
I think convincing reasonably liberal straight people to mess around with the same sex is very different to a gay person doing the same thing because they're already been through the struggle of working out what their sexual identity is and are comfortable with it.