I am of the mentality that handing loaded guns to people is a bad idea.
1. If you are just showing it to someone, make it safe. Drop the mag and lock it back.
2. If you are allowing someone to shoot it, teach them the function of the gun from mag insertion clear thru to firing and clearing, why start a lesson in the middle?
3. If I set a gun down (no kids in my house) I assume any number of things could have happened to it if it were out of my site, I check the loaded chamber indicator on my Glock, then "press check" it using the rear serrations, and ensure return to battery. Keep in mind, I don't set my gun down just anywhere, but still I always check.
One other thing to consider, when you do press check a weapon, it can pull a round forward in the magazine just enough to cause a potential issue, so I always drop the mag, reseat the round and reinsert the mag. I noticed this especially in my Kahr K98 Elite. This may sound like a bit much, but hell, if I have to depend on my gun working the first time everytime, I'm not going to give it any reason to malfunction.
One time, I got pulled over in Utah for speeding (just a little) and I informed the Trooper that I had a permit and weapon. He asked that I hand it over while he conducts his stop. I asked if he minded if I cleared the weapon. When he asked why, I said "Because I never hand a loaded weapon to anyone." He about crapped his pants laughing. He said that was the first time anyone had ever said anything like that. He also said I probably wasn't the kind of person he needed to concern himself with. He gave me a smile and a wave and said "get outta here, and keep it under 90 please!"