One of the most offensive spin tactics is to associate your political opponents with hated foreign leaders and groups (Nazis, Communists, Saddam Hussein, the Taliban, terrorists, etc.).
For instance, in a post last night, Josh Marshall smeared Rudy Guiliani by suggesting his speech was Nazi-like and comparing his hand gestures to Joseph Goebbels:
With Rudy's speech, to riff on the brilliance of the immortal Molly Ivins, I think I preferred this speech in the original German.
On a more serious note, I think it will eventually be clear to people that the Republicans made a major mistake putting Rudy in prime time. Given the state of the campaign, they have to take the fight to Obama. But you need to choose the right person. Rudy comes across as curdled and angry. Great for rousing diehards. But I don't see this speech working with undecideds.
10:27 PM ... What's weird is that Rudy seems to get genuinely angrier the longer the speech goes on.
I will admit he's got the Joseph Goebbels hand gestures down pat.
As I've argued many times before, including here, casual Nazi analogies demean and cheapen the discourse -- it's an easy way to active a series of unflattering associations and attach them to a public figure that you don't like.
On the other side of the aisle, Matthew Yglesias notes that President Bush implicitly drew an analogy between Vietnamese Communists and the "Angry Left" in his convention speech:
If the Hanoi Hilton could not break John McCain’s resolve to do what is best for his country, you can be sure the angry Left never will.
The problem with this construction is similar. Bush is activating the negative associations people have toward the Communists who tortured McCain and attaching them to liberals in domestic politics.