on Jane Friedman site:

Question

Sometimes a freelance editor’s marketing materials (e.g. website, Twitter bio, blog post) will say something like “I’ve edited nonfiction, fiction…and so on”—without naming the books or authors they’ve edited. Or, sometimes I’ve seen editors (and coaches and consultants) show testimonials, blurbs, and books they’ve worked on and/or edited, but none of these represent “work.” Showing a book cover but not clarifying the editor’s role doesn’t help: Did they do substantive or basic editing? Did they help with structure, voice … something else?

For a book, how can an editor show an author what the work involves and how they convey their thoughts/recommendations/suggestions? Does an editor’s work involve notes, lists, track changes, or page rewrites? It would help to know how an editor sees the editor’s role and conveys it—and whether the editor can show examples of their work.

What happens if an author asks a freelance editor (before contract) to show before-and-after examples of the editor’s work on a prior project? Or, would editors be willing to provide testimonials or blurbs that share specifics? It would help to see a list of books an editor has edited, along with the editor’s role (e.g., substantive, basic). Can authors ask for these kinds of detailed references?