Developing a theory of the Skinny Rat Boy archetype in which there is a precise length of too-long stringy hair that shifts the character from piteous but maybe hot?? to Villainy

Mitch from Dazed and Confused: shoulder length hair, innocent
Ziggy Sobotka from The Wire season 2: mostly in "overdue for a haircut" territory, more pitiful than villain but still kinda sucks
That guy in the Arkangel episode of Black Mirror: basically bottom of the neck, absolutely a predator

Further research is needed