I should clarify.

I'm specifically thinking of Linus Pauling with his theories about Vitamin C curing cancer and a former Nobel winning physicist (can't remember who) doing a debunking of global warming based on some flaky arguments. Of course Wikipedia claims that Pauling may not have been completely out to lunch (though I don't really trust Wikipedia when it comes to junk science). And I don't really have any hard numbers, just knowledge of a couple cases and some anecdotes from scientists complaining about the tendency of Nobel winners to turn crackpot.

I suppose this could underline the danger I was mentioning about working with limited evidence as I fell victim in my very own example of it!