"A copy editor reads the entire manuscript while checking for many things: incorrect grammar, spelling, and punctuation; spacing and basic formatting issues; effective writing techniques such as word choice, parallel construction, passive voice over active voice, limited repetitions and clichés, avoiding vague or offensive language; and consistency of spelling and treatment of names, places, objects, actions, etc."
In fact, if you don't prove you have an established platform, with thousands of possible readers, traditional publishers won't even talk to you. No matter how great your proposal is. Oh, yeah, I forgot - before you do or prove any of the above to a traditional publisher, you have to prove you can sell the book and earn back your royalty for the advance. At which time, they will are likely to