Many authors have found that the Kubelka-Munk (KM) scattering coefficient, s(c), of a coating applied to a substrate decreases with increasing coat weight. This decrease is usually explained by a structural/porosity change with coating thickness or a penetration of the coating into the paper In this paper we propose an alternative explanation to the observed decrease in sc, namely the misinterpreted diffuse reflectance factors for non-Lambertian reflecting substrates and coatings. This explanation was recently proposed by the authors; the second part presented here provides experimental support for the presence of a nonuniform reflectance distribution and its influence on KM fitted data. Three different coated systems are considered, using a transparent film, abase paper and a synteape film as substrate. The effect of the surface reflectance of the substrate and of the coated substrate can explain the apparent decrease in sc as an artifact when measuring a sample with an instrument having a d/0degrees geometry.