Bee,
I don't know what it is about scents other than perhaps the chemicals they're created with. There are some flowers I'm allergic to in that the pollen makes me sneezy and drippy and gross, but with fragrances it's worse. If I'm anywhere near a perfume I can't tolerate I get an instant, blinding headache, I become sick to my stomach, my airway closes up and if I'm standing close enough I have been known to break out in hives.

Bobad,
you're dead on with the difference between "allergy" and "sensitivity" but when I tell people I'm "sensitive" to fragrance they often times think I'm just whiney and don't like it...they don't realize it creates the above-mentioned problems. So "allergy" is a better word to use to get my point across that I can't be around it.