Does a stain, like a rust stain smaller than a dime, on the back of a red-seal 1966 $100 take away much value. If it was very fine to AU condition, except for the stain, what would you grade such an item with the stain? and lets assume the stain bleeds thru a little to the front.
Any marks, folds, stains, etc. take away from the value of a min UNC non-marked, folded, stained note but it's not an exact science as to what a perfect note will bring, let alone one with problems. You can search completed auctions for both and see the approximate price difference.
