According to science, the Cardinals are the most hateable team in in the MLB playoffs.
The Wall Street Journal did everyone a favor and created, in essence, a hierarchy of teams to root against. Their results are above, and the Cardinals come out on top. We'd drop their hateability score a little bit, since "Players suspended for PEDs" is not a good category, but even then, the Cards still come out on top. There is some wrong-opinion static about whether "Are fans routinely labeled 'best in baseball?' " is a fair category, since it is clearly targeted. Deadspin believes that any fanbase that does something so obnoxious as to warrant its own category in a hateability index should be docked more than one unit. So -1 for PEDs, +500 for that crap. The Cards are 511.7 hateable, trailed by the Dodgers, at 10.8.
(While we're here, c'mon, $100 million contracts are also not a good reason to hate a team.)