It depends on how the employees treat display guns. I've seen employees take guns out of the case for no reason and sit there abusing and playing with them. Repeatedly dropping the slide, dry firing, slamming the cylinder in, etc. I generally don't buy anything from stores that hire thoughtless employees. I've been to other stores where they don't allow dry firing without snap caps, and insist on safe, respectful handling from customers. I'd buy a display from these stores any day.
But, you run the risk of getting an abused gun any time you buy used too. Carefully inspect any gun, even if it's coming to you sealed from the factory.