If a person hasn't been trained in proper sterilization techniques of equipment that is used on the human body all kinds of bad things can be caught from that equipment, AIDS among them. It's a stretch, I know, but not unheard of. China (and I know I'll get sh*t for this) recently had a huge problem with AIDS being passed in barber shops.
What were they doing there? AIDS transmission requires certain bodily fluids to be transferred. Perhaps if they were shaving people one after another with the same blade, some small amount of blood could be transferred. This is why I shave myself and never share my blade with anyone else. I remeber a store about a family with 3 hemophiliac sons. One got AIDS from a blood transfusion. The other 2 from sharing a razor with him.