As with some of the other posters, I have no interest in men other than the sub / dom fantasy element. It may be, as many have described, the taboo element of sub / gay use which provides the stimulus. It may also be the risk element of surrendering and being tied and used by another man. In life I'm not sissy inclined or attracted to men and thus, so far as labels are concerned, would not consider myself Bi or Gay.
I'm not even sure that should the circumstances arose, where I could experiment safely and discretely, I would partake.... but I might. Hard here sitting typing and thinking about it LOL.