They probably do! have you ever looked someone who's tripping acid in the eye? It's easy to tell. My best suggestion is learn to not care. Paranoia is a big side effect of L, if you don't have fun taking it then stop taking it!
Been to school on acid before. You just gotta practice at being around people. You'll get the hang of it. After then, no one can tell unless you tell them or you're really fucked up.