Source : Webster's Revised Unabridged Dictionary (1913)

Disreputable \Dis*rep"u*ta*ble\, a.
   Not reputable; of bad repute; not in esteem; dishonorable;
   disgracing the reputation; tending to bring into disesteem;
   as, it is disreputable to associate familiarly with the mean,
   the lewd, and the profane.

         Why should you think that conduct disreputable in
         priests which you probably consider as laudable in
         yourself?                                --Bp. Watson.

   Syn: Dishonorable; discreditable; low; mean; disgraceful;
        shameful.

Source : WordNet®

disreputable
     adj : lacking respectability in character or behavior or
           appearance [ant: {reputable}]