In the 1990s, when I was an undergraduate student, in front of the main building of the University of Turin there was a big parking lot, which was always completely full. Two guys were looking after the parking lot every day from early in the morning till very late in the afternoon. They were neither authorized, nor paid by the town council, but they received tips from the students to optimize the space in the parking lot and monitor their cars. The guys did not look very reliable, they wore poor and dirty clothes and they were covered by self-made aggressive-looking tattoos. However, it was not unusual to see one of these guys sitting in a very expensive sports car, smoking stinky cigarettes and listening to loud music from the car-stereo. In fact, when the parking lot was completely full, students used to leave their car to the guys who parked it as soon as a place was available. Imagine a first-year student, who goes to the university by car for the first time, enters the parking-lot and finds out that there is no place available to park her car. Then, one of the unauthorized “attendants” offers her to take the car, park it as soon as a place is available, and then leave the key on it. Judging from the appearance, the guy certainly does not look trustworthy. However, it seems that many other students indeed trust him, since there is a long queue of cars waiting to be parked, including some expensive ones. Would the student leave her car to the attendant? Would she take the number of other cars waiting to be parked as a signal that the attendant is trustworthy? [...]