This behavior is unfortunately common in a variety of settings - caves, woods, mountains, lakes, rivers, springs, etc. People will go someplace beautiful, and then proceed to leave trash, carve graffiti, set things on fire, vandalize trail shelters, etc. Sometimes people that you would think would know better are the culprits - canoeists and kayakers, hikers, hunters and fishermen, even cavers and cave divers.

Humans are strange animals.

Mike