Maybe all the crud avoiders could make stickers to stick on their shirts like a name tag? You know, 'no handshakes + no hugging = no con crud', 'endangered immune system: please don't touch me & give me con crud', 'don't touch me, I have ebola' or something much cleverer. Actually if a vendor sold buttons like that at a booth I bet people would buy them. It is hard to know how to signal these things without other people thinking you're rude, maybe sticking an announcement to yourself is the easiest way. If people still have a problem, well. Haters gonna hate.