Scrolls can be “corrupted” or “misspelled”. This basically acts as a toggle on
whether the confused behavior of the scroll activates: reading a corrupted
scroll while not confused will produce the confused effect and reading it while
confused will produce the regular effect. There is no way to restore a corrupted
scroll to normal.
Possibly, an unidentified corrupted scroll will have its label deterministically
garbled similar to engravings, e.g. “scroll labeled FO0B|E BLe7Ch”. If
identified it would simply show as “corrupted scroll of X”.
Writing a scroll while confused will make the result corrupted. Also,
scrolls hit by water damage or produced from polymorphing other scrolls may be
corrupted.