I don't really agree with you. I've been to several public events in Philly (sporting, among others). NY fans have their fair share of knuckleheads, no disagreement there. But Philly fans can be absolute f*cking animals. Very loyal, and passionate, but they go too far many times.
And I'm not bashing Philly, mind you. My brother-in-law lives down there, and we visit often. I think it's a great city.