you hire a real-estate agent to sell your home. She sizes up its charms, snaps some pictures, sets the price, writes a seductive ad, shows the house aggressively, negotiates the offers, and sees the deal through to its end. Sure, its a lot of work, but shes get- ting a nice cut. On the sale of a $300,000 house, a typical 6 percent agent fee yields $18,000. Eighteen thousand dollars, you say to your- self: thats a lot of money. But you also tell yourself that you never could have sold the house for $300,000 on your own. The agent knew how to-whats that phrase she used?-"maximize the houses value." She got you top dollar, right? Right? A real-estate agent is a different breed of expert than a criminolo- gist, but she is every bit the expert. That is, she knows her field far bet- ter than the layman on whose behalf she is acting. She is better informed about the houses value, the state of the housing market, even the buyers frame of mind. You depend on her for this informa- tion. That, in fact, is why you hired an expert. As the world has grown more specialized, countless such experts have made themselves similarly indispensable. Doctors, lawyers, con- tractors, stockbrokers, auto mechanics, mortgage brokers, financial planners: they all enjoy a gigantic informational advantage. And they use that advantage to help you, the person who hired them, get ex- actly what you want for the best price. Right? It would be lovely to think so. But experts are human, and humans respond to incentives. How any given expert treats you, therefore, will depend on how that experts incentives are set up. Sometimes his in- centives may work in your favor. For instance: a study of California auto mechanics found they often passed up a small repair bill by letting failing cars pass emissions inspections-the reason being that