Unless they're carrying a sign saying "I'm not going to/from class" I'd never know. Because I'd see them and go about my business. I saw a guy in the ER a few years ago who came in wearing one of those Star Spangled uniforms from the 70's or 80's. He wasn't wearing it for class. He was homeless and got it cheap at the Goodwill store. Complete with white belt, which he was wearing tied in a bow.