Why doesn’t sand stick to beach volleyball players?

The sand used in competition is heavily regulated by the International Volleyball Federation. There are no pebbles or bits of shells. The shape ensures a smoother grain. The size is Goldilocks style: not too small or too big. Why doesn't it stick? Because it's designed not to.
Nothing is perfect, of course, so sand is bound to find its way in between articles of clothing and on the skin. That's why some athletes use a special towel to clean themselves during changeovers.