The worst fans I've ever encountered are Razorback fans. I lived in the Bentonville/Rogers area in NW Arkansas for two years and it was an eye opening experience. This was a fan dynamic unlike anything in Texas, the whole state of Arkansas from the time they are born until they die, whether they attended the university or not, live and breath Razorback sports. Everyone of them is so emotionally involved that they exist in this state of ignorant, arrogant, obnoxious self-righteousness and that's win they're winning, with losing comes moral bankruptcy.
I have a lot of specific examples of this, but my wife and I got our first dose a few months after we moved there when the Razorbacks went to Austin to play the Longhorns. Neither myself (Aggie), nor my wife (UH) attended UT, but in Arkansas, if you were from the state of Texas, then you were pro UT. For sake of clarity, we tried to explain to people the dynamics of allegiance with schools in Texas, but this fell on deaf ears, in their mind everyone from Texas was a Longhorn fan and there was no debating it. This all seemed to be perpetuated by this general sense of penis envy for the state of Texas that brewed a hatred for the Longhorns that I have not even seen in College Station. Unless you see it for yourself, you can not truly appreciate the level of anger directed towards UT. Anyway, after the Hogs beat the Horns that day, my wife and I were out running errands where we were subjected to snide comments, horns down, and a general smirk on everyone's face that just screamed, we won, we are better than you. All due to our vehicle still having Texas plates and my t-shirt that had a Texas flag on the front where the pocket would be. The treatment we received surprised us, because we lived in a very nice area, it's not like we lived in the backwoods, dealing with hillbillies, no, this was basically the best the state has to offer.
The experience turned us into Longhorn fans, while we lived there anyway, out of a sense of state pride that, to be honest, I didn't even realize existed inside me until I moved out of state.