Some people just have to pick everything up and twist every adjustment on it .... uh, the way I am in antique shops, but not with people's personal property.
I think it's best to not let too many folks know about collections in your home, but of course we all have our best friends or relatives whom we want to show. With me, it's usually a guitar sitting around the living room that everyone wants to pick up and play a D chord, whether their hands are clean or not.
I keep a lot of flannel rags laying around, so if some of my friends are too grabby with the knives, guns or guitars, I toss them the rag and joking tell them "I'll give you the honors of wiping off my $xxxx.00 ________, after you finger it all up with your sweat, body oils, dirt and skin cells." We get a laugh, but they get the point to not just grab every one because it's there.
JT