In this paper we consider scattering from systems of densely distributed, non-tenuous spheres that exhibit surface adhesion. The Percus-Yevick sticky particle pair function is used to describe the clustering nature of the particles and to include this in low frequency solutions of the quasi-crystalline approximation (QCA) and the quasi-crystalline approximation with coherent potential (QCA-CP). Results from these calculations show an increase in scattering from the adhesive particles which is caused by their larger cluster size. The scattering behavior cannot be explained by distributions of non-sticky particles. Experimental data from optical attenuation by colloidal silica particles is shown to be in good agreement with QCA calculations of sticky particles.