Yeah, in Thai context.
To illustrate: negro (as a noun, not an adjective) is a completely normal term in Venezuela that refers to black people. Would you go around calling Gaffers negro?
"HOLA MY NEGROES, HOW ARE YOU?"
No, you would not.
The transgendered community here probably would not appreciate "ladyboy," much like black Gaf wouldn't appreciate "negro" or gay gaf wouldn't appreciate "marico."
And in any case, like Gaborn pointed out, the OP pretty much can be summed up as "I don't meant to insult anyone, it's just that I was almost tranny surprised." Offensive, in bad taste, embarrassing, etc etc.