Hi, I'm living in Bangkok where there are plenty of ladyboys and I would like to add a few extra tell points.
1. Men in general have thicker skin than women and with some ladyboys you can clearly feel the difference. Some ladyboys focus on making their hands softer but forget the rest of their skin.
2. A bit similar to the sexually forward, guys and girls personalities and behaviors are fundamentally different. This is the easiest sign for me to tell (maybe because I've always been spending a lot of time with girls and normally feel more at ease around girls than guys)