I must say, I've never been asked if *fire* was real, or anything that inane (but then, most demo-type things I've done have been at universities, which may help with that). I have been asked if we fight with live steel (not in those words, though) - um... NO. That's insane. Real weapons and real fighting REALLY will kill people. You have either real fighting, and fake weapons, or fake (a lot more limited than it would have been in period, at least) fighting and real weapons.
Also, I've heard "do you joust?" more times than I care to think about. Which, while not nearly as stupid a question (although how many uni students can afford a horse in the centre of a rather large city?), gets annoying if only for the repetition.