I think a lot of that is comparison shopping. 
No, there are a fair number of “heterosexual” men out there who are kidding themselves.
That, at least, makes sense.
One wonders why you bothered to pose the OP if you were already convinced you knew the answer.
Here’s something you don’t hear me say very often: Starving Artist hit the nail on the head.
Lemur866 made some good points, too. Despite societies constant efforts to make them fit, gender and sexuality really don’t fit into our arbitrary binary social constructs of male/female and gay/straight. It’s much more of a continuum, and there’s no more reason to be attracted to someone on one part of the continuum than there is to be attracted to someone on any other part of it. Why do some guys like pre-op transexuals? Why do some guys like girls with small breasts? Why do some girls like girls with short hair who don’t wear make-up? Why do some guys like guys who wear dresses and make-up and do apalling Tina Turner impressions? People like what they like, and there’s really no better answer for it than that. Or rather, there’s a different answer for every individual who has ever experienced a moment of sexual desire. If you’re looking for logic and consistency in the human libido, you’re doomed to disappointment.
To a different question, SA.
I lived in Hollywood for awhile and had some “experiences” with “shemales”. First- many of them are hotter than many women, and of course they know fellatio better than any woman really can. Now, I personally was not attracted to their penises, and male bodies do not excite me, but when you are little drunk and a lot horny a gorgeous very feminine person sucking your dick is only going to be a turn-off if you are homophobic. I got nothing against gay men (had lot’s of gay friends in Hollywood and West Hollywood), tried an experiment even- but male bodies just do not excite me sexually.
I do watch my share of porn but “Shemale” porn doesn’t really do it for me, most of it emphasises the maleness of the shemale.
Thanks. 
Well, people sometimes do kid themselves. But other times they don’t.
And to expand on Miller’s point, it’s not even a continuum, it’s more of an n-dimensional space. I once knew a quite butch lesbian, and whenever she got a little tipsy at parties she’d start flirting with the femme gay guys. Weird. Thing is though, if she really really were attracted to men, it would make her life a lot easier if she found herself a straight femme man and “passed” as “straight”.
Or the other lesbian I know who was only attracted to super-butch women. You’d think it would be easier to just find a butch guy, but no.
In the end it all boils down to people find hot what they find hot, and in many cases that’s about as much as you can say.
No, Starving Artist had a good point. (There I go again!) You’re presupposing a large portion of the answer you were looking for: that men who are interested in she-males are closeted homosexuals. I don’t think that’s accurate. Men who are attracted to transexuals are usually attracted to the ones who are most succesful at passing as female. They want an idealized female body: boobs, hips, ass, legs, waist, brow, cheekbones, hair, clothes - all traditionally feminine. Plus a penis - traditionally masculine. Out of the ten traits listed there, 90% of the ones he finds attractive are traditionally female. One is traditionally male. That’s enough to make him gay? I don’t buy that. Not unless you’re going to insist that genitalia is the only deciding factor in determining gender.
Oh, and just in case anyone was thinking I was picking on lesbians, it’s just easier to present examples of people who “don’t fit” our preconcieved ideas if they aren’t straight-identified, because with straight-identified people there’s always the argument that, as BrainGlutton points out, they’re kidding themselves.
While it is logically possible that lesbian-identified women and gay-identified men are kidding themselves and are “really” straight, it seems a lot harder to argue than the reverse, that a straight-identified person is really a twisted closet case. There are just too many reasons why someone would identify themselves as straight if they can live with themselves that way.
Oh yeah, her, too!
Agreed. I think it’s a matter of putting all the sexually interesting parts together on a feminine body; besides real world “shemales”, consider the the outright hermaphrodites you see in hentai animation, not to mention written fiction. Nearly all are double sexed with a female appearance.
I can’t see it. I need my women to have a pussy and it is actually the third and ultimate thing that my mind focuses on when looking at a woman. The first is face, the second is overall body, and the third is crotch which is odd because females don’t give you much to look at down there. If the pussy isn’t there, we might as well be looking at the family dog and it isn’t happening. As I have pointed out before, I am actually pretty gay friendly socially but I am 100% straight myself. If I wanted to see any man parts in all of this, I would just whack off to myself in the mirror. I would surely be more attractive to myself than any shemale and also cheaper and with less skeevy baggage.
I guarantee you: If you can think of it, right now, somebody somewhere is masturbating to it.
The up side of the internet: No matter how freaky you are, a little googling demonstrates that there are lots of people freakier than you, so you can feel much better about your kinks.
The down side: For a very small number of people, the above is not true.
But another up side: The internet makes it possible for those people to find each other. 
Here in Thailand, they’re often called “the Third Sex.” The Thai word is “kathoey,” which literally means “transvestite.” They’re quite common here, and it’s not unusual to find one working in an otherwise-staid office environment. I should mention that there is a distinction made – at least there is here;t his seems to be a point of contention in the West, but I assure you it’s a sraightforward distinction here – between transvestites (“chicks with dicks,” if you will) and transsexuals, who have undergone the operation. And sex-change operations ARE big business here.
Who likes them? Well, honestly, the Japanese seem to. At least, a lot of the male Japanese who come here. One bar owner in Patpong hired a bunch of transvestites, or kathoeys, once he realized his Japanese customers couldn’t get enough of them. And I don’t mean just chatting them up in the bar. I mean taking them out of the bar and off to a short-time room or back to the hotel. Then the tourist season ended, and the steady stream of Japanese customers dried up, so he ended up firing all of the transvestites. (An American friend who has lived in Japan for a number of years says he can believe it and tells me of many, um, “unusual” sexual fetishes to be found there. Seems centuries of non-repressive sexuality has made them quite liberated in certain ways.)
In the Nana Plaza bar complex (motto: “Three Floors of Whores”), there are no less than three transvestite bars. One of them has been around for years and years, even before I arrived here. (When I first stepped off the plane here, Ronald Reagan was President in the US.) Casanova Bar is the place, and there used to be a weekly column in the Bangkok Post that detailed the bar scene, written by fellow American Bernard Trink. I remember one week, he asked in his column if anyone could tell which Nana Plaza Bar was a kathoey bar. I wandered into Casanova, and still being a newbie, I was completely fooled. I ws chatting one “girl” up, she wanted to leave with me, but there was just something about her that made me say no, I’d best keep wandering on to other bars. (This was long before I had met my future wife.) She finished her drink, pecked me on the cheek and told me, “By the way, I’m a man.” Aha! So THIS is the bar Trink mentioned. They all looked like real women, too.
However, these days I, like any other long-term farang (Westerner) worth his salt, can spot them quite easily. I’ve amazed visitors who remarked on the beauty of a certain lady when I told them, “Um, actually that’s no lady.” All of us long-time farangs know at least one man who was so fooled by a kathoey that he actually thought this was his “girlfriend.” They haven’t a clue! And you can’t tell them what’s what; experience has shown that they only become angry and defensive and deny the girl is really a man. You just have to let them find out on their own.
One guy even wrote in to a local weekly online column written by a Kiwi farang and his Thai wife (Kiwi = New Zealander). The guy asked whether it was normal for Thai ladies to pee standing up. Seems he had picked up a rather attractive young lady working behind a cosmetics counter in a large department store here, and although he said the sex was great, he’d never seen her naked. She kept making excuses not to have vaginal sex: that time of the month, or it was feeling sensitive, or he was “too big” (which always is such an ego booster that you don’t want to question it), etc. But one night she got up to go to the bathroom in his hotel room and left the door slightly ajar. He could hear a stream of urine pouring in and just barely see her standing in front of the toilet through the crack in the door or the mirror, dunno. Alas! the Thai wife assured him bluntly that no, Thai ladies do not pee standing up, that he’d gotten a little more than he bargained for.
Many of the kathoey hookers on the street and not working in bars are downright scary looking. They are known as expert pickpockets, and often a pack of them will crowd around you, copping feels off you and what not while lifting you wallet and/or cellphone. Not only in the street late at niight, but also major shopping areas in the daytime. The police finally cracked down on the transvestite gangs, but they are still responsible for most of the tourist druggings, guys who pick them up off the street and take them back to the hotel, only to find out in the morning that they were drugged and robbed. Sometimes they don’t wake up, they’re dead.
Some kathoeys undergo an operation to remove their Adam’s apple. They tend to be much taller than the avaerage Thai female. Look at their hands and, especially, the feet; tend to be large. (I knew one tall Thai lady that all the other Thais in her office referred to as “Kathoey Girl,” because she had a lot of the features; she was not very pleased about that.) They can be very beautiful; there’s a big kathoey beuty contest in Pattaya every year, the Miss Tiffany contest, and the winner goes on to compete for the world title at a pageant held in the US. There are at least two kathoey cabaret-show clubs in Pattaya and one in Bangkok (the tour buses crowd the tourists in to see them.)
Many guys who are attracted to kathoeys here would never think of themselves as gay or even bi. And they would never look twice at a farang kathoey. It’s quite a scene here.
If you’re bisexual, wouldn’t it be a case of having the best of both worlds?
Oh, and I almost forgot: There’s a transvestite elephant-polo team here called the Screwless Tuskers. 
Depends on what bits of anatomy you consider to be the “best.”
Bea Arthur