dirty
foul
indecipherable
marked-up
unclear
undecipherable
unreadable
calligraphic
dissimilar
foolproof
illiterate
impervious
inaudible
invulnerable
legible
nonexistent
obsolete
uncalled
undefended
undetectable
unfitted
ungrammatical
uninhabitable
unintelligible
unpronounceable
unrecognizable
untrue
valueless