How did “spreading the wealth” become a dirty deed?

Of all the criticism lobbed at Barack Obama over the last week, the one that gets the biggest hoots and hollers from John McCain supporters is that Obama wants to, in McCain air quotes, “spread the wealth.” Crazy, right? Crazy that a candidate would invoke, as the New Yorker notes, the godfather of free-market capitalism, Adam Smith, who wrote in “The Wealth of Nations” that, “It is not very unreasonable that the rich should contribute to the public expense, not only in proportion to their revenue, but something more than in that proportion.”