I'm a straight guy. I've been in plenty of positions not to be, in threesomes and at times when a gay or bi guy has requested the opportunity to suck me off. I have to say, I enjoyed the oral ministrations of the guys, but I shut my eyes and fantasized that a hot woman was giving me the blowjob. When presented with the opportunity to reciprocate, I was just not turned on by the male body (btw, in case you think I'm a selfish SOB, it was always clear that reciprocation was unnecessary--I didn't promise anything I didn't deliver or intimate something would happen that didn't--in each case the guy requested it and I think they got off on just sucking off an otherwise straight guy).
On the other hand, and I think this is true for other straight guys, the thought of a passable she-male (a pre-op transvestite) or a very feminine hermaphrodite excites me. It's not the cock that is the problem. I'd certainly suck my own if I had the flexibility (tried it... failed... damn!). I certainly don't think there's anything wrong with being gay or bisexual, and I applaud people for being open minded when it comes to sexual expression. I just don't get turned on by men. Cocks are cool, though. They're fascinating, really. Some, I must say, are far more appealing visually (at least to me) than others, but they're still a very interesting body part. Something that grows in size, becomes hard, yet still with soft skin, has a large head with a unique texture... Put something like that on a woman, with soft skin, sexy breasts, a pretty face and sensual lips--it becomes very interesting. (Not more interesting that what ladies already have, though. Female parts are wonderful!)
I think that's why shemales and hermaphrodites are sexy even to otherwise straight men. It's not that we don't appreciate cock. In fact, it's almost guaranteed that we've played with a cock a lot more than we've played with woman (I refer, of course, to our own phalluses--phalli?). I often wonder how many guys, if they could do it in total secret, would enjoy sex with a hermaphrodite or a shemale. In my book, What Happens in Vegas Stays... On the Highlight Reel, I explore the question when I put the main character into a threesome with two sexy women, one of whom is a hermaphrodite.
I'd be interested in getting a woman's perspective on this (as well as comments by guys). Would it be sexy for a woman to have sex with a shemale, or a hermaphrodite? Would it seem to be the best a both worlds?