Haha, oh man. I've heard some horror stories. Like Maureen Freely. She worked closely with her friend and fellow author Orhan Pamuk to translate his novel, Snow. They exchanged drafts, comments, and suggestions before meeting up in Turkey and going over the text together for several days to come with a manuscript they were both satisfied with.

And then some copy editor in England decided that he didn't like the main character's motivation and changed it.