When Does An Editor Go Too Far?

I was chatting with a writer bud who repeated a comment her editor had made about her writing. It was both unprofessional and unkind. Keep in mind that someone liked this author's writing enough to contract the story.
Now add into the mix that the editor is both author and editor. This is always a yellow caution sign for me. Are you going to get a supportive professional editor or an editor who imposes her or his writing style on you? I've had both sides of the spectrum. On the positive side of the equation, one of the best editors I've ever had was an author/editor.
But regardless of whether an editor writes for a living and edits on the side or is a full time editor, that person has a responsibility to treat his/her authors in a professional manner. And vice versa. As authors, when interacting with our editors and publishers, we need to show them the same professional courtesy that we expect them to show us.
Authors, what do you think? When does an editor go too far?