I was taught when I borrowed a gun, I was to return it unharmed, clean, with a new box of ammo. (Similarly, if I ever borrowed a car or truck I was to return it unharmed, clean inside and out, with a full tank of gas.). Here’s hoping those folks who are enjoying your generosity were taught the same.
I don't mind lending a rifle, especially a stainless one, but don't want anyone else running a cleaning rod down my bores. JP I did lend a 6mm Rem rifle to a neice and she was seen leaning on the butt with the muzzle stuck in the dirt a couple of inches. Her cousin cleaned as much of the dirt out as he could before handing it back to her, with admonishment to never do that again. (She's shooting Expert in the Service now. And my rifle is still shooting fine.)