A lot of straight guys can safely be described as "bi-curious." They wonder about the grass on the other side of the fence, but don't want to live there. They don't even want to own the property. They want to step over the fence and poke around awhile, and then back into their own yard again. And a lot of straight guys who are bi-curious are really only curious about one thing: the one thing that women lack. They don't find guys attractive. So you get She-Males--people who look like women except for that one thing women lack and she-males have--a cock. She-Male movies are a niche but they're gaining in popularity, especially as plastic surgery improves and the female part of the equation gets better. A lot of early she-males still looked like hairy guys in drag, but each generation of she-males looks more convincingly female, while retaining the one last link to being male. But a lot of guys (including me) are put off by watching she-males with other guys, because the guys aren't the attraction here, it's the girls.