I'd have to disagree with the Digimon thing. That was my favorite show when I was younger. It was decent, at least. Hardly deserving of "never should have existed". Looking back on it now, it's not a work of art, but it was meant for kids.
I think most anime/manga are decent in some sense for SOME person. But personal opinions tell me excessive fanservice and teen girl drama make some shows unbearable.