I like cooked spinach...but not canned spinach.
Canned spinach is slimy and bitter.
Frozen spinach is pretty good when heated correctly and not overcooked.
Fresh spinach cooked with fried bacon added is pretty good.
But lots of people don't like spinach.
I think it's mostly because they were given canned or overcooked spinach and it turned them away from it.
I was that way with zucchini...I was served some overcooked, slimy zucchini when I was a kid and I instantly "didn't like zucchini!"
But when I was older I was served some lightly sauteed zucchini cooked in butter and I found it delicious!