I hesitate to speak up before I've actually experimented with this idea myself . . . but perhaps someone will have a spare switch around and want to find out for him/herself
It is my understanding that these rocker switches are injection molded plastic (of some sort), which would mean that the material is solid and of the same composition throughout. In other words, if you scratch beneath the surface, you hit exactly the same material as that on the surface. If this is the case, the only difference between the surface and what lies beneath is simply the level of smoothness or gloss/sheen.
It is also my understanding that the "grey-ish" finish which eventually turns up on our old rocker switches is simply "oxidation" of the plastic (I believe almost everything oxidizes sooner or later, including our blood).
My suggestion is that these switches can simply be polished back to their original colour and sheen.
I would (if and when I get around to removing mine) start with wet/dry sand paper of, say, 1000+ grit to remove the heavy oxidation, then progress up the grit numbers till I was happy with the surface. I would finish with a buffing wheel and compound, to the sheen desired (probably matt to satin, but not gloss, but I'm not sure of the original look). The sandpaper and compounds used would be the same as used for "flatting" (as you Brits say) the colour or clear coats on a car and are commonly available where I live in grades up to 2500 (but go much higher, if you look around for "micro" abrasives). In my case, I'm a guitar finisher/refinisher and work exclusively with nitro-cellulose lacquer (which used to be applied to cars before it was catalysed with "acrylic", and then replaced altogether with enamels and then urethanes). This is the process used to level and then bring back the gloss on a lacquered guitar body. With the right grades of abrasives, you can bring back the surface and sheen on any reasonably hard thing, including plastics (and windshield glass, for example).
So . . . any takers? Anyone willing to confirm my thesis for group's edification?
Randy
[An example of "micro-abrasives" from Lee Valley, in a size suitable for our application:
http://www.leevalley.com/en/wood/page.a ... 3243,43245]