This was true for me, at least.
I grew up a fan of Alabama Football and, in MLB, the Atlanta Braves (like every other kid in the deep south) and Boston Red Sox (randomly grew into being a big Wade Boggs fan... I like to pretend the Yankee years never happened). Yes, I realize that being a fan of two MLB teams makes me a sports bigamist. I came about it honestly though, so don't lump me in with the rest of those soul-less scoundrels of my generation who grew up fans of Florida State, the Dallas Cowboys, and the Chicago Bulls.
This wasn't necessarily true 5 years ago. Alabama had just done the right thing and fired Head Coach Mike Price for his reckless decision to sleep with a stripper while on a recruiting trip. And the Boston Red Sox were like that guy Trent talks about in Swingers: "the PG-13 guy that everybody's REALLY hoping makes it happen." Except they couldn't make it happen, losing to the Yankees once again.
But now, in 2008, I root for the Evil Empires. In the 4 years since the 2003 ALCS failure, the Red Sox have won 2 World Series titles. And because Americans everywhere jumped on the bandwagon & embraced Red Sox fever after the '04 ALCS comeback, profiteers seized the opportunity to flood the culture with everything "Red Sox". ESPN inundated sports fans with nothing but talk of "the Yanks & the SAWX," as ESPN's Michael Wilbon is accustomed to saying. There was even a movie. Used to be that Red Sox fans framed their rivalry with the Yankees like a Star Wars movie: Steinbrenner was the Emperor, various characters were Darth Vader, and the highlight clips of the Yankees' inevitable march through the postseason could be played to John Williams' "Imperial March" musical theme. That sentiment has completely reversed now, though, with the Red Sox on top.
You can't watch a Dolphins or Alabama football game without laboriously listening to a conversation between a wanna-be Keith Jackson broadcaster & some has-been coach/player color analyst that concerns either (1) Saban's now false statement to the media in his final days in Miami, or (2) Nick Saban's 4 million dollar per year contract. And it is BEYOND clear that the two individuals engaging in said conversation either (1) are offended that Coach Saban lied to a fellow media member ("Solidarity, Brother!") or (2) are simply jealous.
Nevertheless, it is what it is. So since Satan is our head coach, I've heard it all. We cheat on the field, break the rules on the recruiting trail, have no sense of cultural perspective (e.g. the Saban 9/11 & Pear Harbor remarks), are a win at all costs people, have no soul, etc. Nobody likes us.
I'm slowly learning to appreciate this turn of events, though. Rooting for the "nasty boys" of the sports world is kinda fun. My guys are now kind of like that other guy Trent talks about in Swingers: "like that guy in the Rated R movie -- the guy you're not sure whether or not you like yet. You're not sure where he's coming from." There's even a slight psychological advantage in terms of the other team being intimidated, whether that takes the form of Saban's blitz schemes, Josh Beckett's fastball, or that lethal Brady/Moss connection.
Heck, even my country is looking more & more imperialistic. "It is useless to resist, Iraqi citizens..."
I say long live the Empires.