"The Giving Tree" I loved as a kid, when the tree was just being loving and generous.
As an adult it was an irritating book about a codependent tree and an entitled kid.
I still like The Giving Tree, though now it's just because the tree ends up happy after a long, truly crappy life. It has the happiest ending it possibly could, short of re-writing the whole thing. Kinda like when Odysseus' dog dies after twenty years of neglect, but it's okay because at least he got to see Odysseus one last time. But of course Odysseus's prolonged absence wasn't his own fault in the first place.
Crap, now I'm tearing up. Argos, that was the dog's name. And you know what, Odysseus should've gone to him. I don't care if would've blown his cover, he was already planning to kill everyone anyway. Bah.
Back to The Giving Tree. The Rainbow Fish has pretty much the same basic message, but it appalls me. The fish is oh so pretty with its rainbow scales, and the other fish are jealous so it learns to share by giving each of the other fish one of its scales. So apparently the moral of the story is that if you have something others want, you have to share it with them, even if that means tearing off pieces of your body. And the book is not only popular, it's been turned into a whole series.