Several Raiders in the late 70s and early 80s also developed a bad case of rap sheet. Thus the tie in. Steelers/Raiders has to be one of the best playoff rivalries in NFL history.
I'm aware of the reason why we have that reputation and to me it's rather short sighted. In fact I'll take that a step further...before we moved to l.a., the players took on the reputation you described, after we moved to l.a., the fans took on that reputation. (Admittedly, the "fans" in l.a. were ready for a fight and it didnt matter who you were and I'm beyond happy we dont reside there anymore).
That's why a lot of Raider fans like myself take being called a "criminal", even in jest, so personally. To me it's no different than a conservative being called a fascist. I don't have a criminal record, I obey laws like most everyone else does and this is true with the rest of Raider Nation.
If it seems like I'm blowing this out of proportion, well, so be it. What most of you call gospel truth--the "criminal" Raiders and our fans--I call slander.