Think that if someone writes a book or a biography with your name, it can damage more or less the image of your person or company, but in the end you can always “blame it”. However, with ghostwriters, what will you say if there is a mistake? I doubt that saying “hey, I didn’t write that” is going to fix anything. You should hire someone you trust 150% because you are basically making your name available to their hands. It is better to collaborate and update your ghostwriter with everything. What better than to look for the best possible hands?