But when is it fair to be fair?

In a recent discussion of Pope Benedict XVI, John Aravosis asks a “fair” question:

When is it fair to call a Nazi a Nazi?

I’m in a generous mood (and not interested in lengthy analysis), so I’ll disregard the possibly rhetorical nature of the question, and treat it with the logic and respect it deserves.
So, in answer to the question of when is it fair to call a Nazi a Nazi. . .
I’d have to answer, um . . .
Hmmmm………
When it’s fair to call a Communist a Communist, that’s when!
UPDATE (04/28/05): Anyone who thinks it’s fair to call a Communist a Communist should read this (via InstaPundit).