Bava Metzia 81: Put It Down!

A dilemma - when one is exempt from the liability of a borrower, does that mean he has no liability or just as one who is paid to watch over it. Plus, why a donkey who isn't sold is a different case from a gift of pottery, for example. Also, the parameters of the paid guardian, and the requirements of an unpaid guardian, and the interaction with the one who owns the item being guarded. The formulation of statements may make the difference.