I begin by considering a 'dishonest' salesman, I formalize his disposition by the hypothesis that y exceeds a. To have an interesting problem I assume further that a is positive, that is y > a > 0. … The potential customer reasons backwards: 'If I enter the showroom and make a purchase the salesman wil sell me a lemon and my pay-off will be —6, which is less than zero — my pay-off in not buying a car at all. So of course I should not enter the showroom'. And he will not. We have thus a unique equilibrium of the game where no transaction occurs and where each party enjoys a pay-off — of nil. This is worse for both than the (non-equilibrium) outcome where a reliable car is sold and where the customer and the salesman enjoy @ and a respectively. A mutually beneficial transaction is thus unrealized.

QUESTION: How does signaling or reputation mechanisms break this lemons-market equilibrium in practice?

Diego Gambetta, Trust - Making and Breaking…, loc. 896