Phil Plait of Bad Astronomy writes eloquently on debating pseudoscientists:

Debunking fringe theories is usually not trivial. For example, Richard Hoagland has been making his (mistaken) claims about Mars for literally decades. The breadth and depth of his claims is astonishing! It would take forever to debunk everything he says, as it would for most pseudoscience theories. And every time you debunk one thing, they pop up with another claim, instantly ignoring that you just destroyed their last argument. This is another reason most scientists don't bother debunking wacky theories.

... I took on the gist of the claims, and I don't bother with the hundreds or sometimes thousands of minor details. Destroy the foundation of their theories, and all the little claims flutter to the ground as well on their own.

But then, inevitably, the issue of a debate comes up. Nearly every major (in the loose sense of the term) pseudoscientist has challenged me to a debate at one time or another. Both McCanney and Hoagland have publicly called for me to debate them on, for example, the "Coast to Coast AM" radio show. In almost every case, I have refused.

Why?

To Hoagland's followers, the answer is obvious: I'm scared to debate him, because I know he will win. That is silly, and obviously so. If I thought I were wrong, why would I write my pages in the first place? Moreover, and this may be more pertinent: why go on C2C and talk about it? After all, there is a chance that one of the people whose theories I am trashing might call in! Clearly, there must be another explanation.

There is; read more. Or listen to an mp3 of the classic lecture Science and Pseudoscience by Imre Lakatos, with the transcript here on a memorial web site.

Among the pseudoscience out there today (hallmarks: paranoia, revolutionary, anecdotal, it's the only way, 100% cure, proprietary formulas, grandiose, expensive, medical miracle inspiration stories, poor references) is this ebook on how multiple sclerosis is a sham while the author has the real cure. For a fee, of course.

I challenge any media representative to investigate: the claims I make against medical leaders, my treatment approach, and the testimonies I supply on this website, to reveal that there is abundant medicald ocumentation which proves, the advice medical doctors and neurologists give to MS patients that lesions on the brain and irreversible deterioration of the nerve myelin sheath are responsible for the symptoms of multiple sclerosis and that the symptoms of MS cannot be overcome, is nothing short of absolute nonsense!

He goes on, and on. "I am willing to appear on any television program ..." I'm sure. But I'll heed the two scientists above and engage in debate. Instead, just a snicker at this banner. So bad it's good camp.

Dr. Phil will likely not debate either, though he and Oprah get a direct attack: "Dr Phil is completely wrong in saying: 'being overweight is nobody's fault but your own.'"

Why? Another pseudoscience cliche.

After Receiving Horrible Treatment At A Brisbane Hospital At Age Thirteen, I Am Speaking Out Loud And Clear, Against Leaders Of The Medical Profession Who Allow Pharmaceutical Drug Companies To Control The Medical Industry.