I assume that the reason for koshering meat is to get rid of the blood.
If that is the case, if someone eats gribenes, which are fried chicken skins, do the skins need to be koshered? What if one were able to carefully peel away the raw skin from the rest of the meat assuring that there was no blood in it?
For that matter, if one were to eat sheep's wool, rooster combs or chicken feathers, would any of these require koshering, if there is no blood in them?