I used to be all huffy and offended by it, but several posts made here by people this year have helped shift my opinion.
There are straight, gay, bi, genetic men and women out there. There are people who prey on those who are barely legal, barely able to support themselves, naive, all sorts of things. Unless they're just sleezes straight up looking for one night stands specifically because you're a girl with a penis, don't judge too harshly. And then remember that women are crudely hit on, receive lewd comments, unwanted advances, and soforth all the time. Is it wrong? Yes, but it's the nature of humans.
For people raised in strict cultures, who have repressed their own sexuality or possible interests, we're very curious creatures. Some of us, even if we plan to transition, don't deny ourselves the comforts of having partners. Relationships are way more complex than any forum-guideline can walk you through. Some people go gay for the right person, some people go straight for the right person - sometimes the individual really is what matters, other times people discover a world they had never gotten to know before, or consider possibilities they had never been allowed to. They could always be bi and appreciate you post op as well as pre.
If you're a non-op, or on a low dose of hormones to get feminization without the desire to transition (which can be for a variety of reasons, some temporary, some life based), finding someone who is attracted to you isn't a bad thing at all. You have to work with what you have, so unless you want to live in seclusion...
If you plan to go all the way, as long as they're not just using you, and you're both on the level, and they're respectful of your wishes about your body, what's the problem? A lot of times, my penis won't co-operate in the bedroom because there's only certain applications that interest me. I feel bad when I can't do something my partner wants to do, but, as long as they're ok, and as long as we like each other, are attracted, and can work out something where we both are satisfied, it's called dealing with reality. Sometimes straight men like it in the <not allowed>, sometimes women who are fully content with being a woman find happiness from penetrating people. My girlfriend tells me that most of the time she considers my <not allowed> like a strapon - I certainly don't suddenly believe I'm a man when we're having sex and don't think she's one when she uses her actual strapon.
If you transition at 25, 30, 35, and you have no dating experience, or dated the opposite sex of who you really wanted to, or your only experience dating was awkward high school level relationships, or even worse, 'online boyfriend/girlfriends' , you are *not* going to know how to handle real relationships, how to deal with the stresses, the give and take, compromise, the way games and manipulations can occur, the warning signs to watch for, and how to truly appreciate a good thing. It's really easy to screw up a good relationship when you lack experience, and when you are desperate for the feeling of acceptance and love, you are prey to be taken advantage of.
I would say a <not allowed> <not allowed> is someone who is specifically interested in transsexuals for the sake of utilizing their genitalia as if they were their birth gender, with sexuality being the primary focus of the relations.
For example, I like butchier women. If i find a girl who works out, doesn't dress or act frilly, doesn't like makeup, and acts like one of the guys - but fully appreciates being a woman - sign me up. If I find a young transman who's in early transition and exhibits a lot of those qualities, and date him because I see him as a more masculine woman rather than a man even though I know how he wants things to be, that's <not allowed> chasing.
If a guy comes to me and says he wants me to sodomize him while wearing my leather boots and corset, because he's totally straight, but you know, just likes it when a woman has a penis and just happens to put the penis in him, that's <not allowed> chasing.
