No, I've been to enough games to verify. Philly sports has earned it's moniker. As someone who's been subjected to a lot more fanbases/experiences, it doesn't happen everywhere.
I don't what your experiences are. 60%+ of people at Eagles' games aren't white trash. Way too high, but it does fit the narrative rather well.
When I go to games it's usually with a group of 50+. Sure, a couple of goofs might find their way into the group, but nowhere close to 30/35 of the 50 are anything close to a normal white trash definition.