Ok, I'm a bit confused. In several places on this board I've seen John and Judy referred to as stand ins for porn stars.
I thought they were body doubles for an ordinary movie. He said something about some other body double job he'd done.
They aren't actually having sex, so they can't be porn stars. They are free to talk while working so their faces obviously aren't on screen.
What kind of porn star doesn't do all their own scenes anyway? It's not like "yeah, I'm a porn star just do close ups of my genitals, but please use someone else' body (oh but please use my face)".
They're stand-ins, not body doubles. Their job is to take up the positions the actors will be in and stay there while the technical people sort everything out - lighting, camera focus and angle, that sort of thing. This takes ages, and is both boring and tiring, so you don't want to subject your actors to it. Someone once said that filming is like war - long periods of boredom, punctuated by moments of terror. I don't know about terror, exactly, but certainly the moments of excitement are few and far between. I've been there, done that, in a very humble capacity - believe me, there's nothing glamorous about it.
John and Judy have to be naked because the actors will be naked, and they have to go through the movements the actors will be making, so that the techies can get everything right; but they don't have to speak the dialogue or act any emotions, so they're free to talk. This is obviously where the comedy comes in - the absurd contrast between the simulated intercourse and their shy, hesitant and very chaste courtship. I think they're sweet.
You're welcome. Yes, they don't have to have film-star looks, though obviously they have to be about the same size and general shape, and the same skin tone, as the actors. A thankless task, generally.
I guarantee that no porno I've ever seen went to the trouble of using stand-ins to perfect lighting, angles, sound, dialog, etc. It was just humpin' and pumpin' on videotape.