There are legitimate concerns. As a professional business broker I have specialized in confidentially selling businesses for over 20 years. I require purchasers to sign a confidentiality and non-disclosure agreement as well as fill out a financial profile unless I am aware of their financial status through other avenues. The use of an experienced business broker / intermediary can buffer you from most of the problems that could arise. Make sure not to give proprietary information such as  customer lists or trade secrets until closing. Beware of "no money down" or "let me work in your business before I buy it" purchasers. They can be very dangerous.