Same people who get headaches from power lines and hear AM radio via their fillings.
We once had to spend several days in India with an American lady who insisted she was allergic to: moving air, chilled water, ice, non certified organic vegetables, most all spices, and the list went on. And as a native New Yorker she was an insufferable b!+@% if anybody made the mistake of serving her a prohibited item or mistakenly placed her near a fan or air conditioning. Watching her react to India was memorable and we could never figure out why she came. Some people should not be allowed to have a passport.