Uhhh, I don't know if I'm grasping at straws or, on the contrary, just pointing out the obvious, but what if, aside from the obvious attempt at representing/parodying a teenager that is into everything alternative and "progressive", Sam is actually intended as an expy of the Hex Girls?
I mean, the girls identified themselves as Eco-goths and were clearly feminists, all three things Sam is supposed to always be preaching about. They're all somehow related to the supernatural, and...
Just look at them, dude!