Over lunch, the Bad Astronomer sent us over to read Cumbrian Sky, and phoenixpics’ description of why moon hoax believers will never ever ever be convinced that we’ve landed on the Moon. It’s a good read.
I, fortunately, have never run into a person who denied the Apollo Moon landings. I have no idea what I’d do if I met a person like that. I suppose it’s likely that I’d be polite and change the subject, but there is at least a possibility that I would tell the person to get medical attention and that they’re a total idiot before then politely changing the topic.
Someday I’ll find out.