A friend of my wife's swears she's completely allergic to fish and that just the smell of it is enough to make her sick for days. She absolutely loves my Thai cooking and in particular yum nua (Thai beef salad), and has eaten it at our house many times before. As yet we haven't told her that it's drenched in fish sauce.
Haha that's a perfect example. I have noticed some people's "allergies" are in their head. I think if they had bad food once in their life they can't ever eat it again. A case in point my buddies wife, she's straight off the boat from Cuba.
She has about 10 major "allergies", fish being one of them. In Cuba obviously the masses don't have access to top quality fish even though it's a freaking Island in the middle of some of the most productive tropical waters. Anyhow, they serve frozen fish (goggle eyes) we commonly use as bait here and their product is of dubious quality. Of course she got deathly sick from it and is now allergic.
She says she's allergic, however if you give her fresh fish, she can eat it, no problem. If she knows it's frozen she says she will get sick. If you give her frozen and don't tell her she doesn't get sick. It's weird and I wouldn't try it on everyone because fish allergies can be real but I am sure you get my point.