I know the Eagles fans have that kind of rep for sure.....what's funny is that I have 3 friends here that are Eagles fans all from the Philly area, they are the complete opposite of what you defined.....Knowledgeable, sane and they wish Reid would have never left....
some of my Eagle-fan friends fit that description also, so they exist. but they're a minority in comparison to the fan-base at large. at least in my observation.