Luckily, you'll find most airsoft players are honourable and call their hits. At least in my experience. Hell, it happens that people get hit and don't realize it, don't feel it, etc. Someone with a BB bouncing off the back of their vest at 50 feet away while running full tilt... well, it's understandable that he didn't feel it. But the ones that repeatedly don't call their hits eventually get known for this. There is no room for that in airsoft, and a player who deliberately doesn't call his hits. And this is a small community. Word spreads quickly and one will quickly find himself ostracized from the airsoft community.