I've always been somewhat suspicious of Godwin's Law. Imagine the following scenario:
"They are acting like Nazis!"
"Ah! Godwin's Law! You lose!"
"B-but, they're herding Jews onto trains, and burning Synag--"
"What? You're still here?? You already lost by comparing them to Nazis!"
In other words, sometimes comparisons to Nazis are apt and necessary. Otherwise, what does "Never Forget" really mean?