Oh, yes they do, IMHO. If not an editor then a very good proofreader. Probably two or three of them, with one to read after the other, because everyone will find something to fix in even the big house's releases. No one's perfect But...we can strive to be the best we can.

Going from writing THE END to publication can't not have 3rd and 4th eyes on the work to be sure it's the best it can be, especially within budgetary constraints. The industry is so full of unprofessionally presented books that the ocean of books out there makes it ever-harder for readers to find the books they want to read.

There has been a dumbing down of readers, and writers, in the last decade and we must strive to be the best we can be if we want to rise above the flotsam and jetsam to be noticed.