I get irritated to no end with "bandwagon" fans. You know them... the douche bag rockin' the Patriots jersey with the Yankees hat. Surely you noticed the sudden emergence of Tampa Bay Rays apparel right around the '08 World Series (they had that Lakers jersey on underneath just in case). You might hear it rationalized with something like "I expect excellence out of 'my' teams". I guess loyalty and sticking with a team through thick and thin isn't a priority for everyone.
I asked myself the question: who would piss me off more? The guy in the Peyton Manning jersey that has been a bandwagon fan for several years, or the guy in the Drew Brees jersey that has been a bandwagon fan for several months?