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, such as car repairs or medical services, are characterized by severe informational asymmetries between sellers and consumers, leading to fraud in the form of provision of insufficient service (undertreatment), provision of unnecessary service (overtreatment) and charging too much...