Hummmm! I've never quite understood this way of thinking, but, to each his own. This is one reason Texan fans should not biatch so much about the number of Cowboy fans that show up at games, esp when we play them. Once a Cowboy fan always a Cowboy fan, and fans of other teams obviously are not willing to change.
I've been a NINER fan since I was a kid, won lots of money off my brothers who HATED them, but, I will NEVER pull for them when they play the TEXANS! Any other time, YES, I want them to kick ass, but, NEVER when they play us.