The Rayleigh scattering of light at resonance with the ground state exciton transition in quantum wells is studied by means of a microscopic model. The disorder-induced localization of the exciton center-of-mass leads to characteristic features of the scattered intensity which can help understanding the outcome of secondary emission experiments. In particular, the connection between time-resolved scattering and energy-level statistics, and the enhancement of the backscattered intensity in angle-resolved measurements are discussed.