We compare the behavior of car mechanics and college students as sellers in experimental credence goods markets. Finding largely similar behavior, we note much more overtreatment by car mechanics, probably due to decision heuristics they learned in their professional training.

Credence goods markets suffer from inefficiencies caused by superior information of sellers about the surplus-maximizing quality. While standard theory predicts that equal mark-up prices solve the credence goods problem if customers can verify the quality received, experimental evidence...