Why hire an editor?

Editing and proofreading are essential.  First impressions count, especially when your reader may have hundreds of manuscripts to sort through.  If your document is riddled with spelling and punctuation errors, it won't matter how brilliant your ideas are; the reader will be put off by the presentation.  An edited document will allow your ideas to shine through.

To put it in more concrete terms, editing is often what will set a manuscript apart from the rest.  This might mean the difference between an "A" or a "C" from your professor, or it might be what gets your manuscript out of an editor's slush pile.