Marketing practices like Money-Back Guarantees (MBG) are prevalent in many expert service markets but are often decried for taking advantage of poorly informed consumers. In this research, conducted in the market for In-Vitro Fertilization services, we empirically test two contrasting views of MBG practices – the “light” theories, like signaling and insurance which advocate the positive impact of marketing practices and the “dark” theories, like firm sorting and aggressive treatment that postulate the negative impact of such practices. Our analysis is conducted on a large and unique longitudinal dataset that includes clinic-level treatment and outcome statistics for almost all IVF clinics in the U.S., fertility clinic characteristics, and information on state-level insurance mandates and demographic characteristics. Using an instrument variable approach to account for the endogeneity of MBG decisions made by fertility clinics, we find more support for the “light” and positive impact of marketing practice. Our results suggest that MBGs can work as signals of quality despite the incentives for clinics to engage in opportunistic behaviors.