Mike C. From Writing Forums Speaks on Editors...

Editors work both freelance and in-house with publishers. Major publishers will have a team of editors (though in the current climate that may switch more to freelancers subcontracted by job).The only Agents who retain or recommend editors are generally scammers - "We love your book, we can definitely sell it, but it needs polishing, our guy can do that for $500..."If you obtain an agent they will likely suggest what needs polishing, but they'll expect you to do it. Freelancers often operate as 'Book Doctors', of variable quality. If your writing is up to snuff, you don't need them. If you want a professional second opinion, shop around. Two I can recommend are Martha O'Connor The Writer's Consultant and Barbara Rogan who offers both writing courses and manuscript evaluation.