The low-frequency permittivity and conductivity increments and the static conductivity of well-characterized latex dispersions and plugs have been measured over a wide range of ionic strengths. We have investigated the effects of adsorption of the neutral polymer polyethylene oxide on these electrodynamic phenomena. It is shown that the counterion mobility in the double layer is significantly reduced by the adsorbed polymer. A model is developed to describe the retarded motion of ions in the gel-like polymer layer, which is considered a Brinkman fluid. The required ionic and polymer distribution functions are obtained from a self-consistent field model. Furthermore, zeta-potentials were inferred from streaming potentials of close-packed latex plugs. Since a significant part of the conduction is due to ions behind the shear plane, it was necessary to make use of the plug conductivity data in obtaining the correct zeta-potentials, especially at low ionic strengths. The zeta-potentials of the polymer-coated surface are lower than those of the bare surface which indicates the shear plane to be shifted outward. The reduction in counterion mobility and the shift of the shear plane is also shown by the plug conductivity data.