I saw buffalo bills at miami dolphins (nfl), dragged my wife there in 1999. Dublin was a pre season for Chicago bears . If i can see the great game i will. But i have been a Chicago bears fan since 1986 (oh the glory year) i only got into NCAA last year and USF were the first team i saw.
It depends on the level you watch, I'm a season ticket holder with a small team called Dagenham and Redbridge, we have 1800 fans to a game and we all drink and chat with the opposition. Rugby is the same, you can sit next to a guy giving him and his team sh!t the whole game and when it's finished shake hands and wish them well. When i went to buffalo at miami i loved that we were all mixed in.