Once, when I was walking past an older couple in the parking lot, the guy had to LOUDLY comment to his wife, "Who knows what's in that thing, he could be smoking anything.". I just had to backtrack and say to his face, "I'm not smoking, and I know exactly what's in this thing. Do you guys know what's in those cigarettes?" Basically, I don't care what anyone thinks, and I tend to meet fire with fire of my own. However, if someone was to ask me a question politely, I would certainly politely respond.