The exception to 404.9(B) allows for a switch to be ungrounded if it is "provided with a faceplate of nonconducting,noncombustible material.
Question is " Shouldn't this requirement also require the same for the faceplate screws" ? Although I see this alot in existing residential installations,very seldom do I see anything other than metal screws.

Many years ago when I was contracting; we always grounded the switches. I feel it makes for a safer job. How many times have you installed a plactic plate and found the home owner changed the plate before final inspection. Now working as an inspector, I have to follow the NEC. I would like to see switched grounded, I know plates are changed and home owners will put on any thing they think looks nice.

Doesn't the exception to grounding the yoke only apply to replacement switches where no grounding means is available.

But in those instances I agree with txsparky nylon screws would be a great idea.

I seem to remember that in a "multi family housing STATE code, you needed non-conductive (nylon) screws) on switchplates.
It may have also applied to hotels/motels.
There was a thread relating to this a while ago, and I suggested that McMaster Carr still had nylon 6-32 screws in the catalog.
John