I've done it once. It was not nearly as cool as some folks think. You start to realize how many hiding spots are in the house. I was also quite certain that I was the idiot that left the door partially closed as opposed to someone had broken in. It's a calculated risk based on what you are looking at. I tend to not slam someone for doing it, or for not doing it. Each their own. As long as you now it's risky and proceed accordingly. I'm not one to call 911 when I'm not sure it's an emergency though.