Is cash for books legit?

Could you please elaborate on the legitimacy of cash for books transactions? Are there any risks associated with such arrangements, and how can buyers and sellers ensure they're engaging in a secure and fair exchange? Additionally, are there any regulations or laws that govern cash for books transactions, and how do they impact the process? It would be great if you could provide some insights on how to spot potential scams and protect oneself when participating in these types of deals.