Why aren't any of the "aliens" in Prince of Space wearing any underwear? Theorys are welcome.
Because their society is backwards. They go out in public without underwear and then put it on in private. There's nothing more erotic to them than a female putting her underwear on.
I'm going with the Emperor's new clothes theory. They THINK they are wearing the finest pair in the galaxy, and their culture is the only in the galaxy to own them, but in fact they aren't. Sad really.
Scottie
To answer my own question, I thought the director (if he was male) was gay and had a fetish of seeing chicken-like aliens in tights, clearly with no underwear on.