Perhaps. But you could probably use a few specific metrics to judge the quality of a nonfiction book, particularly if you're looking to hire a ghostwriter.
1. A book should have a central idea that is easy to understand. Simple = good.
2. A book should be elegantly written, meaning its chapters each have a clear purpose and flow in a pleasing way, with a clean structure and a conversational tone.
3. The best books offer clarity: they get to the point and don't have a lot of extra words or jargon.
4. Finally, a book should be stimulating. It must evoke emotion and curiosity. It guides readers right to the heart of key moments of transformation, both in your own life and in the lives and careers of your clients. You should be choosy about what to include.
Your book isn't really about you (wait...what?). Stay with me. Your book is about the reader. Stay relentlessly focused on that one person and how each part of your book exists to help her.
Your book should be conceived and executed with a heart of service. How will your book serve and uplift others? How will it move them closer to their goals? How will it help them see the world differently?