I only know about people who seek mtfs. There are different types of "Admirers." Some have gender identity differences of their own and prefer to be with others who they regard as more understanding of their differences. These people tend to be different than most of the men who are into "->-bleeped-<-" porn or whatever you call it.
Those type of men are 99% straight. People like to call them gay or bi, but if you talk to them on a one-on-one level or examine where the porn can be found in a porn store, you will realize that most of them identify as straight. Now... why would a straight man desire a woman with male genitalia? There are many different reasons.
For one, men tend to associate their manhoods with lust, power, and other positive characteristics. A woman who has male genitalia is thought to have these traits which they (mistakenly) think can only be found in the male domain. I have a transwoman friend who worked as a[n online sex worker] on the web and she said that most of her clients IDed as straight men and wished to be dommed by her. They saw her [penis] as a source of power.
Other men assume that a woman with a cock would be lustful like a man and not have the hangups that most cisgendered women have about sex due to their oppressed upbringing. I've noticed that most of my tswomen friends are more open to trying out new things sexually or are willing to do things that their counterparts won't. I talked to one male admirer about this and he said that this was why he preferred transwomen.
There's also the fact that vaginas can be confusing and scary for some straight men. Have you ever heard of
vagina dentata? It's a myth about a vagina with teeth. As for confusing, most men don't have vaginas to practice on and many women don't tell men what to do in bed so some guys feel hopeless when they encounter them in real life. They have [penises] and they figure they know how to please a person with a [penis] (since they can please themselves) so they prefer women with [penises].
I'm sure there are other reasons I haven't mentioned, but these are the ones I have observed and confirmed.
