As you may or may not know, under a different persona and name I write erotica. I recently received the manuscript of my second novel back from the publisher and it had been supposedly copy-edited.
I just spent six-plus hours going through her (the copy-editor's) changes in Word. I probably kept 30% of them. The rest were:
* removal of all Oxford commas and all commas before "and"
* addition of commas before every conjunction except "and", even where not necessary
* adding spaces before and after each ellipsis and em-dash, even when they ended dialogue (so they didn't run directly into a quotation mark, such as --" or ...")
* setting off every possible parenthetical phrase with commas, even when not appropriate
* adding actual parentheses in the text
* adding spaces between compound words that don't need spaces between them, and removing every single one of my dash-concatenated compound adjectives
* moving commas, ellipses, and em-dashes all over the place in dialogue -- when they were clearly there so that, when read aloud, the dialogue would sound more like a person actually speaking it
* obliterating intentional use of repetition and intentional misuse of comma list rules for dramatic purposes (she did x and y and z and a, but still his b was doing c)
* having absolutely no knowledge of how to recognize and edit for properly-used parallel structure
In her defense, she did pick out a couple of places where I needed to be more precise or improve the flow, and she did make some changes that improved the writing. But on the whole I rejected the majority of her changes. The same thing happened with my previous novel, and that time around I actually noted why I rejected them. This time I just rejected, accepted, or edited.
So my question is this: how do you tell your publisher that her chosen copy editor sucks?
I'm not perfect. I know this. I would never presume to say that I am the best copy editor on the planet, or that I can publish something with no revisions, or that everything I do is grammatically-perfect. However, I would say that of all the things she marked as possible errors, when you remove all the unnecessarily-added spacing issues, only 10% needed to be changed, and I accepted another 25% as "okay, fine, I'll just accept these because they're not a big deal and they don't change the book one way or the other."
But I have another publication (a novelette) with them, and if this editor destroyed a book that takes place in Florida in 2008, what's she going to do to a novelette that takes place in a fantasy world?
(Apparently this editor has worked on multiple NYT bestsellers, though since I only have her first name, I don't know how to verify that.)