Cursed scroll of uncursing always displays a message "The cursed Foo glows in a black light." no matter what BUC status it had before reading the scroll.

For example using a cursed scroll on a blessed amulet of life saving produces "The cursed amulet of life saving glows in a black light.".

Uncursed scroll of uncursing works properly and using one on a cursed amulet of life saving produces "The cursed amulet of life saving glows in a silvery light."