This is what I think a good editor should be and perhaps a little bit about me, as well. A good editor should put his writer first. A good editor should attempt, to the best of his or her ability, to make a good manuscript become a great book. The writer and the editor must communicate closely during all phases of creation, and make every effort to become a tightknit team with a capital T, TEAM.
A good editor doesn't put money first; it's the book that matters. Money should always be secondary, alas, to some people, it's very very important. I'm not saying that money doesn't matter. It should be the last thing you're thinking about. Take the time to establish a fair payment plan with your writer; after all, you wouldn't want to feel strapped either.
No one is perfect, but a good editor takes the time to eliminate all mistakes in a manuscript, if possible. Take time to read each sentence carefully, adding and subtracting words, to make that same sentence read better than before. Make plenty of comments in the margin of the manuscript to communicate your intent with the writer clearly.
When it comes time for the final edit, should you charge the writer for that service? Maybe not.. Perhaps it should be FREE. After all, no one is perfect and you do have an obligation to eliminate error and elevate the manuscript to a great read and a fantastic book. Thank you all for reading this and God bless... Moneysaver Editing