Nikole Edwards said a ghostwriter completes an entire project as a solo work under the name of another author. With a ghostwriter, your work is done for free before you start your next writing project.
A good ghostwriter relies on the knowledge of an author, which is not needed if the author does not know his subject well. The ghostwriter fills in the gaps and ensures that the knowledge deficit of the author does not harm the book.
Quoting past authors is a good standard for a good ghostwriter. Many ghostwriters want to claim credit for working on a book, but if you want anonymity, they tend to demand more for it. Ghostwriters working on high-profile books are not allowed to tell you unless they have signed an NDA with the author.
Many authors, including yourself, are appalled by the idea of ghostwriters. If you don't like the idea of someone else writing your book and hiding the benefits of ghostwriting, change your mind.