Guy wasn't stupid, but he was CRAZY.
I was looking at a Ruger P98 (I think?) and he wanted to demonstrate the decocker lever to me and a buddy. He picked up a box of Hornady 'tracer' rounds, I forget what they were called and stuck 1 in the mag while explaining to us the these were great "for shooting 'spooks'". After inserting the mag in the gun, he racked the slide, chambering a round. I'll give him some credit here as he aimed the gun in a relatively safe direction (away from us but at the front wall of the building which was about 6 feet from a busy road). Needless to say, by this time I had taken about 3 giant steps away from him. He reached his thumb up and snapped the decocker, scaring the s**t out of me when the hammer dropped at full speed toward a loaded round.
I never bought the gun and never went back. Guy really scared us both, but we laugh about it to this day.