This policy keeps really weak manuscripts from dragging down our percentage. There are a lot of good editors out there, many of them fellow drop-outs from mainstream publishing. Giving false hope to a writer whose material will never get published isn't just unethical, it's cruel. Much the best way, of course, would be to sample the wares, something most editors don't make possible. If we think it will never get published no matter what the editor does to it, the author does to it, or God does to it, our report tells the writer why.
Fees vary widely.
Some editors charge more than we do and some charge less. If the author can't afford the fees and the book clearly has the potential to be a big seller, we occasionally agree to be paid with a percentage of future earnings. I used to do one on self-editing. One of our editors still does, another editor can do characterization workshops, Ross has a dialogue workshop, etc. Writer's conferences give you the chance to hear or even meet authors, agents, editors, and other people who could be valuable contacts along the long bumpy road to publication.