Glazed slipper pads

[sosidge]

Would I be right in thinking that the material that slipper pads are made of will not be effective it it has a "glazed" appearance.

And would rubbing the pad surface down with some fine sandpaper be good practice to get some more life out of it?

Referring to a Tamiya Durga by the way although the pads seem to be a similar friction material to other cars I have used in the past.