The Collaborative International Dictionary of English v.0.48:

Besmirch \Be*smirch"\, v. t. [imp. & p. p. Besmirched; p. pr.
   & vb. n. Besmirching.]
   To smirch or soil; to discolor; to obscure. Hence: To
   dishonor; to sully. --Shak.
   [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

42 Moby Thesaurus words for "besmirched":
   bedraggled, befouled, blackened, blotchy, darkened, defiled, dingy,
   dirtied, dirty, discolored, drabbled, draggled, fouled, foxed,
   foxy, fuliginous, grimy, impure, indecent, inky, maculate, muddy,
   murky, smirched, smoky, smudged, smudgy, smutty, soiled, sooty,
   spotted, stained, stigmatic, stigmatiferous, stigmatized, sullied,
   tainted, tarnished, unchaste, unclean, unvirginal, unvirtuous