Nasty production detail concerning the rats used in the film

Who gives a rat's ass...

It sounds like made-up nonsense of a writer in desperate need of publicity (who has ever heard of T Hart?). As others have remarked, why would one need to boil rats in order to "dye" them? And why would only "some" or "half" of them die when boiled? Moreover, not caring for their survival during transport seems a hell of a waste. He needed 10,000 rats. Did he order 20,000 to account for the fact that half of them would die en route?

I understand where some of you are coming from, but I'm afraid you've been duped. Didn't happen that way, at least not according to any reliable source. I find it funny how much debate there is considering it didn't happen.

Werner Herzog generally lets these stories fly or even contributes to them. He said, "You can't fight a rumour with facts. You can fight a rumour only with an even wilder rumour." And when you think about it, he's got a point. When you confront a rumour with facts it just sounds like denial. Exaggerated rumours (like the rats were dipped in boiling water) make it absurd.

Similarly, Roman Polanski and Jack Nicholson got tired of explaining the elaborate process of making it look like Nicholson's nose was cut in Chinatown (1974). So instead they just started telling people they actually cut Nicholson's nose and were done with it.

So, here's the story:
"Where did you get the rats?

From a laboratory in Hungary. Customs officials checked the medical certificates at every border, and somewhere en route one of them opened a box to check the contents and promptly fainted. When we bought the rats, they were snow white, so I decided to have them all dyed grey. There was a huge factory in Germany that produced shampoo and hair dye, and they always tested their products on rats because the texture of rat hair is similar to that of humans. I visited this place along with Henning von Gierke, a painter and art director who did the set design for the film, and Cornelius Siegel, a special-effects expert who taught at the University of Bremen. Cornelius was the one who set the glass factory on fire in Heart of Glass and single-handedly built the clock in Nosferatu, with all its moving parts. After talking to the people at this factory, Cornelius designed a massive conveyor belt. We put the rats into wire cages, dipped each cage into the dye for a second, washed every rat with lukewarm water, then dried them all using a system of hair dryers, otherwise they would have caught pneumonia. Even today there are claims floating around that the rats were mistreated and that some died while being transported to Delft, even resorting to cannibalism because they were so hungry. The fact is that we ended up with about five hundred more than when we started. There were also allegations that we submerged each rat into a bucket of boiling grey paint. I hereby offer the even wilder truth of the matter: we boiled the rats for such a long time that they volunteered to turn grey."
-Werner Herzog's A Guide for the Perplexed

There you have it.