Bias Bias (Meta-Bias?)

From Bryan Caplan:
Why is the psychologists' approach so superior to the economists'? Simple. Economists reject all-pervasive testimony on lame methodological grounds. Psychologists, in contrast, aggressively cross-examine this all-pervasive testimony, and empirically expose its all-pervasive perjury. Despite what they say, people really are selfish, businesses really are greedy, students really are lazy, and workers really are materialistic. Econo-cynicism has a firm basis in psychological fact.
Of course, a "firm basis in fact" is hardly the same as "unvarnished truth." Some deviations from narrow self-interest handily survive cross-examination. Voting really is largely unselfish, workers really do obsess about nominal pay, and managers sincerely hate firing anyone. The point, though, is that the economic way of thinking is on much stronger empirical ground than economists themselves have managed to demonstrate. Though we've often belittled psychology, it's ably served us for decades. Perhaps if economists give psychologists some much-deserved credit for Social Desirability Bias, they'll be more eager to vouch for the value of what we do.
Does social desirability bias apply to discussions of social desirability bias? Will people be more likely to detect social desirability bias if they believe signalling acceptance of social desirability bias theories are socially desirable?

It sounds like I'm trying to be funny, but I'm not. Whenever we start talking about systemic biases, we raise implicit epistemological questions. How do we know that the bias exists without priming for it? But how can we prime for it without compromising the results?

In some ways I think the means-end approach of e.g. Ludwig von Mises neatly and effectively sidesteps this problem, but then again I have never been very warm to behavioral econ.