I'm very picky about fish. I like tilapia, flounder, cod, and tuna, but the mere smell of salmon makes me gag. And if I see any grey shiny scaly thing on a fish...ugh.
I really hate any vegetable that's been cooked to a colorless limp pile of sludge. And I cannot handle the texture of cooked spinach, especially canned spinach. I like raw spinach and sometimes I'll wilt it (by dunking it in hot water), but the texture of cooked spinach is just....wrong.
Beef liver. Again, it's a texture thing.
Onions. I'll use them for seasoning in cooking but I do not like anything with noticeable onions in or on it.
Iceberg lettuce. It's like chewing on crunchy water.