The fear of being suckered is such a strong social and psychological phenomenon that political movements, and bodies of law, have been built around it. This review offers a framework for understanding how the psychology of feeling suckered affects legal decision-making. Feeling exploited or scammed is a core and widely shared aversion, and yet also a malleable construct, subject to framing effects and triggered (or untriggered) by subtle situational cues. The stakes for the sucker inference are high; people worried about being cheated predictably react by refusing to cooperate in prosocial activities, and by retaliating. The flight-or-fight response has deep implications for legal decision-making, undermining investment in cooperative enterprises, dispute settlement, and efficient social policy. Finally, the review considers the unique ambivalence toward suckers themselves—the competing feelings of sympathy and scorn—and how that ambivalence plays into underreporting of legal harms, misattributions of consent, and victim blaming. I conclude by suggesting that the ambivalence offers opportunities for productive legal interventions to reward trust.