I am very fortunate in that I don't seem to be allergic to anything, so I didn't really understand people with extreme allergies when I was younger. It can be hard to relate to, when you don't have those experiences. But I get it now - my husband is sensitive to a lot of artificial fragrances. He can't go down the cleaning products aisle at the grocery store, his face gets all blotchy and he starts sneezing and almost wheezing. His mom is the same, but worse - she pretty much can't handle ANY fragrances. When I first started coming to her home (been with hubs since high school) she kicked me out once because I had perfume on and it really hurt my feelings, simply because I didn't understand where she was coming from. I thought she didn't LIKE my perfume and was being mean to me, I didn't understand it made it hard for her to breathe!! Now we have a fantastic relationship, and I'm very careful to not even use hairspray if I'm going to be visiting her, and she had me buy special unscented deoderant that I think doesn't work for beans but it's all she can tolerate me to have on, so I deal with it. Small price to pay to visit with loved family members.
So if you find someone who's unsympathetic...don't take it personally. Most likely they just don't understand.