I think the reason it still works either way in some cases, is because magnets also produce eddy currents in the body, which are composed of electricity. Perhaps because the eddy currents are created directly in the body, they don't need to be adjusted for travel through organic matter? Who knows, I don't have a plasma device so I can't say any definitive statement on this.
I have definitely noticed no penetration problems when running frequencies on a pulsed magnet, though.