Optical surface quality plays a significant role when considering laser applications. Specifically, short pulses, high pulse energies and shorter wavelength impose high requirements on surface characteristics. Amongst others, scatter losses, absorption, or the damage threshold place high demands on the specification of an optical part, and each application will define the order in priority of these properties. We have conducted several experiments to investigate in the impact of surface characteristics of polished substrates on the performance of coated optics. In this contribution we report on the techniques used to qualify dielectric coatings for excellent power handling capabilities based on the substrate surface finish.