They're wrong about how to be wrong, because they think they can calculate around it. Calling yourself "Bayesian" and calling your beliefs "priors" is so irresponsible it erases all of that; it means you don't take responsibility if you have silly beliefs, because you don't even think you hold them.
Do you have specific examples in mind? (And not to put too fine a point on it, do you think there's a chance that you might be wrong about this assertion? You've expressed it very confidently...)