When you say "sexing up" do you mean between the sheets/in bed? Maybe they don't, maybe they really are clueless with no imagination, or maybe just selfish, me, me, me.
You mean they won't do anal sex or swallow?? Now that takes a real man who has the confidence and self assurance of their own self. Some will NEVER get that, so your doomed to less than 100% satisfaction with such a person. Best move on.
If your just talking physical, maybe they just are not experienced with Women either, not just Ladyboys. Maybe they are not REALLY "comfortable" in their own skin, and perhaps have difficulty admitting they like the "third sex" as much as anything else. Maybe afraid/scared their friends or family etc will call them "gay" or worse. Maybe they are just tired physically after a hard day at work, travelling, or the beach or where ever. Maybe they are not a machine. It works both ways here and there has to be a connection, or all bets are off. I'm sure most that have been around a while have the unfortunate experience of a "star fish" who does NOTHING but lie there, so I can understand your annoyance and frustration.