The Collaborative International Dictionary of English v.0.48:

Unblemished \Un*blem"ished\, a.
   Not blemished; pure; spotless; as, an unblemished reputation
   or life. --Addison.
   [1913 Webster]

WordNet (r) 3.0 (2006):

unblemished
    adj 1: free from physical or moral spots or stains; "an
           unblemished record"; "an unblemished complexion" [syn:
           unblemished, unmarred, unmutilated] [ant:
           blemished]

Moby Thesaurus II by Grady Ward, 1.0:

119 Moby Thesaurus words for "unblemished":
   Christian, absolute, beyond all praise, blameless, bleached,
   blotless, bright, chaste, clean, cleanly, creditable, dainty,
   decent, defectless, dirt-free, erect, estimable, ethical, fair,
   fastidious, faultless, flawless, fresh, full of integrity, good,
   high-minded, high-principled, highly respectable, honest,
   honorable, ideal, immaculate, impeccable, indefectible,
   indefective, infallible, innocent, intact, inviolate,
   irreproachable, just, just right, kosher, law-abiding, law-loving,
   law-revering, manly, modest, moral, noble, nonpolluted,
   of cleanly habits, peerless, perfect, principled, pure,
   pure in heart, purehearted, reputable, respectable, right,
   right-minded, righteous, ritually pure, sexually innocent, shiny,
   sinless, smut-free, smutless, snowy, sound, spotless, stainless,
   sterling, sweet, tahar, taintless, true-dealing, true-devoted,
   true-disposing, true-souled, true-spirited, truehearted, tubbed,
   unadulterated, unbesmirched, unblotted, uncontaminated, uncorrupt,
   uncorrupted, undamaged, undefiled, unfaultable, unhurt, unimpaired,
   unimpeachable, uninjured, unmarred, unmixed, unmuddied, unpolluted,
   unsmirched, unsmudged, unsoiled, unspotted, unstained, unsullied,
   untainted, untarnished, upright, uprighteous, upstanding, virtuous,
   well-scrubbed, well-washed, white, whitened, worthy, yeomanly