Wondering where disgusting behavior comes from (usually meaning a lack of civility and/or penchant for misdirected linguistic abuse, but also general grossness, like someone snorting snot at you during lap swim when they know you're there), I came up with this typology:
Sources of Disgusting Behavior
a) Nature - i.e., Some people are just disgusting and it's too unnatural for them to change.
b) Environmental Reflection - The world gives hell, and some people insist on reflecting it back without restraint for their own catharsis or lack of a 'filtery' or 'spongey' quality.
c) Psychological Warfare - This is pretty common. Get someone's head down for sadistic kicks or a dominant position.
Lest this list not appear exhaustive, art, for instance, or humor, can fit partially into multiple categories.
a resource for the next witnessing, like once I step outside.