Best example of obnoxiousness: Their willingness to literally fight for a terrible team.
Raiders fans have always been there to intimidate anyone who dare enter their stadium donning anything but the silver and black. Sometimes (if no other options are available), they simply take that aggression out on each other:
You have to wonder why it is that they're still so passionate as to brawl in the men's room, when they haven't sniffed the postseason (or even a winning season) in a dozen years. When you enter a stadium and have a chance to experience the fist of a fellow fan, you know you're dealing with a terrifying and obnoxious base.
That gets you ranked up high, but there's still an entire town even more widely known for the antics of their followers.