The three-body approach to the single-scattering optical potential proposed by Tandy, Redish, and Bolle is tested in the context of ..pi..-d scattering where the various approximations are compared with the exact solution of the Faddeev equations. For ..pi..-d scattering we find that the integral equations derived for the Kerman-McManus-Thaler form of the single-scattering optical potential are markedly superior to those of the Watson form. Our analysis includes a study of the convergence properties of the various multiple-scattering series encountered.