How do you know they wore them? Do dancers wear underwear with their tights? (Hell, do wrestlers? Or bicyclists, for that matter?)

I will say, though, this is one reason why I like today's Hollywood superhero outfits, most of which are closer to Roman armor than dance-wear. Spandex looks goofy and, let's face it, you don't want to worry about the bulge in your shorts every time you're facing the masters of evil.