The Collaborative International Dictionary of English v.0.48:

Smutty \Smut"ty\, a. [Compar. Smuttier; superl. Smuttiest.]
   1. Soiled with smut; smutted.
      [1913 Webster]

   2. Tainted with mildew; as, smutty corn.
      [1913 Webster]

   3. Obscene; not modest or pure; as, a smutty saying.
      [1913 Webster]

            The smutty joke, ridiculously lewd.   --Smollett.
      [1913 Webster] -- Smut"ti*ly, adv. -- Smut"ti*ness, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

smuttiness
    n 1: the state of being dirty with soot [syn: smuttiness,
         sootiness]
    2: obscenity in speech or writing [syn: smuttiness,
       dirtiness]