I'm finally reading Rick Perlstein's Nixonland, and I laughed out loud when I read this passage about the vulnerability of Jerry Voorhis, the California Democrat who was the first victim of Richard Nixon's red-baiting:
Voohris possessed an added vulnerability: He had once been a member of the Socialist Party. Not a Communist, but for the upright burghers of Southern California's suburbs, to whom property was as sacred as anything in the Bible, the distinction was sufficiently arcane to be moot.
This remains true of modern American conservatism, although I'd argue that today conservatives' failure to distinguish between Obama's moderate liberalism and communism, or socialism is willful. It's less that they don't know the difference than that they don't care.