Aqueous dispersions of different smectite-type clay minerals were probed by ion-exchange of methylene blue (Mb). The evolution of the absorption spectra with time demonstrates the importance of the strength of the Mb-clay surface interaction, which is affected by the colloidal nature of the suspension and typical clay characteristics. A strong Mb-surface interaction is observed for clay minerals with tetrahedral substitution and a large basal surface area. Mb species adsorb in a more polar environment and show well-resolved bands. Their mobility is small. When the Mb-surface interaction is weaker, Mb-Mb interactions and interactions among the clay particles dominate. This is the case for octahedrally substituted clays with a large edge surface. Mb species experience the influence of the surrounding water phase and of neighboring Mb molecules. They remain mobile, even for longer aging periods. The absorption spectra evidence a less polar, "undefined" adsorption environment.