The question put to us was "does playing naked change the sound".
Answer; YES... but not in a good way. The back on the guitar or mandolin resonates along with the top, thus producing sound. When the instrument back is pressed on the body of the musician, the sound is dampened. More damping on bare skin than on a flannel shirt.
Violins, the way they are played, as well as most instruments played with a bow, are not dampened by being pressed against anything, thus the produced sound is fantastic.