Not all zoos are bad but a lot of them are just money making machines.
Sea World and places that keep sea mammals in captivity may offer some education - but it's nothing that can't be taught through film and books. Dolphins and killer whales doing tricks for food is not educational. And it's a disgusting form of entertainment. More often than not they're not even helping those creatures.
As for dog shows - never understood the point of them. It's basically a pageant for animals. And humans get to feel better about themselves for having the "better" dog.