One of these years the Crips and the Bloods will be fraternal organizations as well. If groups have staying power they become institutions, even if they're never "acceptible" to society at large.
When I was a kid I remember my mother's dread of running into the Hells Angels in the mountains during the summer. We'd head out on camping trips, but she always had the provision "If the Hells Angels are at the campground, we're not staying." I haven't recently heard of the Hells Angels being used by parents as Boogey Men to get their children to mind them, but that's not to say they don't. It all seemed rather exciting when I was a kid.
I think my kids and I would still probably leave the campground if they pulled in today. I might give the kids the explanation that they may be "okay," but we don't know, and to quote Aesop, "you're judged by the company you keep." If you hang out with perceived bad apples, then people are going to treat you like one.
Very simplistic, but we mothers do what we can to equip our children to live long happy lives. I understand my mother's way of thinking now.