The Collaborative International Dictionary of English v.0.48:

Unobjectionable \Unobjectionable\
   See objectionable.
   [break]
   [1913 Webster]

WordNet (r) 3.0 (2006):

unobjectionable
    adj 1: (of behavior or especially language) free from
           objectionable elements; fit for all observers; "good
           clean fun"; "a clean joke" [syn: clean,
           unobjectionable] [ant: dirty]
    2: not causing disapproval; "it was an innocuous remark";
       "confined himself to innocuous generalities";
       "unobjectionable behavior" [syn: innocuous,
       unobjectionable]
    3: not objectionable; "the ends are unobjectionable; it's the
       means that one can't accept"

Moby Thesaurus II by Grady Ward, 1.0:

78 Moby Thesaurus words for "unobjectionable":
   OK, above suspicion, acceptable, adequate, admissible, adorable,
   agreeable, all right, allowable, alright, appetizing, attractive,
   better than nothing, condonable, decent, defensible, desirable,
   dispensable, enviable, exciting, excusable, exemptible, expiable,
   fair, fairish, forgivable, good enough, goodish, inculpable,
   inoffensive, irreprehensible, irreproachable, irreprovable,
   justifiable, legitimate, likable, lovable, moderate,
   mouth-watering, not amiss, not bad, not half bad, not so bad, okay,
   pardonable, passable, pleasing, presentable, pretty good,
   provocative, reasonable, remissible, respectable, satisfactory,
   seductive, sufficient, taking, tantalizing, tempting, tenable,
   tidy, to be desired, tolerable, toothsome, unarraignable,
   unblamable, unblameworthy, uncensurable, unexceptionable,
   unimpeachable, unindictable, venial, viable, vindicable,
   warrantable, winning, workmanlike, worth having