Obviously, there is none. The point is, assuming the answer to be "yes" isn't a slam-dunk, and (in general) may not even be a good bet.
(The mechanical reason for Betteridge being true more often than not is that if a journalist want to make a claim but can't (because the facts don't support it) they frequently phrase it as a question. If the thing they want to imply were true, they'd just say it.)
