Rule for identifying quacks

Gary Taubes says in an interview:

And then I wrote a book called Cold Fusion, on the great scientific fiasco of the 1989-1990; and when I came out of that I said: Look, anyone, when I was talking to journalists -- one of my rules of writing now is whenever someone invokes Galileo as a personal role model, he's a quack. Meaning? Give me an example. Well, the joke is in effect I just invoke Galileo by using epicycles and perfect circles. But the argument is literally the paradigm is wrong. And as long as your paradigm is wrong, if you believe obesity is just about eating too much and expending too little, this energy balance idea, it's all calories-in/calories-out, you can't get the right answer.

That is a good rule. Besides Galileo, I would add Nicolaus Copernicus, Nikola Tesla, Albert Einstein, and Thomas Kuhn (or paradigm shift).

I am not saying those people are all quacks. They were each brilliant in their own ways. But they are patron saints to the quacks.