Cool, but at least one of them completely admitted she's got a lot of issues (nonviolent, so we were pretty good friends until we fell out of contact) and another was actually very violent - against me and at least one other former partner I know about - and SHE was the one who told me about it, not the victim. We were kind of a thing for a bit, but eventually the sex wasn't worth the constant gaslighting and attacks.
Then there was one who said she'd dyed her hair "mental breakdown red", but I never got to know her well enough to figure out how much of it was a joke. There was a "this is a joke, but like all jokes, it's not completely out of thin air" energy about it.
Truth be told, I know one girl who has a similar hair colour and seems completely sane. Don't know her too well, kinda stopped talking after school and she was pretty introverted back then, but she's been rocking it as her style for a few decades now. The common thing between the others is that they all did theirs after some traumatic event, which is where I got the hypothesis that radically changing one's appearance might be a trauma response - hence my nickname for it: mental health red.