I have never used the snow plow technique. I have always just cleaned my CD-4 records the same as my regular ones, with a sponge in the sink with Dawn detergent and it has worked excellently. As I have written elsewhere, playing CD-4, for me, is no different from playing regular two channel records. Any distortion is extremely rare.
One experience of mine, which may support the snow plow mechanism, is that some of my CD-4 records, which were difficult to play originally (e.g. my copy of Hugo Montenegro's first record), have gotten much better the more they are played, the example I gave, for one. It now plays almost perfectly. Does more and more dirt get scooped out of the carriers in the groove at each playing and I am sweeping that away when I use the Discwasher brush before each play? I think that's it.
Doug