Listening to people on this site, we may as well root for "meteor!" for pretty much every World Series matchup. NYY or Bos? Can't blame anyone for hating them. Philly? Worst fans in sports! Tampa Bay? Fans don't support their team and don't deserve a title. Texas? Nolan Ryan is an ass. St. Louis? Smug fans! Pirates? Can't root for them because we hate Steelers fans. ...and so forth.
At some point, it gets ridiculous and you're left with just "hating" pretty much every WS team each year instead of enjoying the Fall Classic.
I think the only teams I would actively root against in a World Series are the Yankees, Red Sox, and (if they ever made it) the Cubs.