"The researcher, Cormac Herley, looked into so-called “Nigerian scams,” named for the African nation where the scammers often claim to reside. The emails typically seek a cash investment and promise a lofty payoff, often linking themselves to off-shore corporations or royalty. Herley’s algorithm-rich analysis found that the obvious spam clichés are a deliberate attempt to weed out potential victims who are too savvy to fall for the scheme—and in turn make the most of the human capital required to secure funds from the people who are duped.
“Since gullibility is unobservable, the best strategy is to get those who possess this quality to self-identify,” Herley writes, and the scheme ingeniously lines up the most gullible recipients in one swoop. Those who are left “represent a tiny subset of the overall population” but nevertheless a lucrative one for the spammers."