I’ve gone back and forth on this myself, and honestly, it depends a lot on your goals. Careful self-editing can catch a lot, especially if you take breaks and reread with fresh eyes, but it’s really hard to spot everything in your own work. Proofreaders usually notice small but important things like repeated words, awkward phrasing, punctuation issues, or inconsistencies you’ve become blind to. That stuff really does affect readability and how professional the ebook feels. When judging quality, I’d look for sample edits, clear pricing per word, and reviews from other authors. From what I’ve seen, the best services don’t rewrite your voice, they just polish it. For many authors, that final pass makes a noticeable difference.