When talking to a librarian or accountant who happens to be transgender, shemale or ladyboy would generally be highly offensive. I've seen a tg person go off nuclear when someone refered to shemale porn, even though it's the correct technical term, after all.
Around here, though, we're perverts
so I wouldnt' worry about using shemale or ladyboy to refer to people in the porn business. As long as you understand that away from the camera, these are real people who are only in it for the money. Many are trying to pay for transitioning, and can't find work anywhere else, so they get sucked into porn. In any case, they deserve our respect when we're not jacking off to them.