It is sad that disgusting that things like this go on and there is no way of really controlling it. If you really thought about it you would never eat out. I think it can happen at high end restaurants as well as it can at fast food restaurants.
"Herpes Burger" sounds like a good name for a restaurant. Not! Man what a sick bastard. I think they need to make you register if you have herpes of the mouth. If you do you should be barred from working fast food. I know that sounds discriminatory, I'm half joking, but still I don't know if I'd want someone with Herpes on their lips making my food.
Want something more disgusting? Let me share a story: Lol. That's the risk of eating out especially on unknown food stands, I guess.:/
I don't really worry much about those things happening. When I eat in a restaurant, I usually take it on faith that the people I am being served by with aren't sociopathic. Besides, I have ocassionally lodged a justified complaint, but I am always nice about it..so I don't think I have anything to worry about.
I was working in big restaurants of one big hotel. The biggest one that was also my primary one had 1000 guests in one day. So it was a buffet restaurant. There was a chef who would do crazy stuff because he was not a good one or a fast one. So he was always late. i was helping in kitchen. Sometimes he would drop a full pot of spaghetti on floor. Pick it up because he could not afford not to have that pot outside, and serve it like it was nothing. He would come and tell me, because we had breaks for meals, George, do not eat pasta today. Eat in small places, please. It is much better because the pressure on chefs is less and they are not so crazy.