Great post mate.
I know how you feel.
I went behind the scenes at seaworld once, and while there are some pretty bad animal places out there I do think that Seaworld - at least on the G'coast is a good guy. Some of the animals are rescued and actually can't be rehabilitated back into the wild.

I think their program of educating people more on these animals and the importance of looking after them and their environment is great. And they do so much research that should help their survival in the long run.

Obviously the way they are cared for and kept is of the utmost important. As to them doing tricks.. hard to know if they like it or not. It could be their way of playing and having a good time. I guess that would be easy to work out. If they have to mistreat them to train them.. obviously the animals don't want to do it. If they train pretty easily they probably do.

Also in captivity it may give them stimulation they might not otherwise get it.

It is a tough question I guess.