The Collaborative International Dictionary of English v.0.48:

Blotchy \Blotch"y\, a.
   Having blotches.
   [1913 Webster]

WordNet (r) 3.0 (2006):

blotchy
    adj 1: marked with irregularly shaped spots or blots [syn:
           blotched, blotchy, splotched]
    2: marred by discolored spots or blotches; "blotchy skin"

Moby Thesaurus II by Grady Ward, 1.0:

51 Moby Thesaurus words for "blotchy":
   besmirched, bespangled, bespeckled, blotched, dingy, dirty, dotted,
   dotty, flea-bitten, flecked, fleckered, frecked, freckle-faced,
   freckled, freckly, fuliginous, grimy, macular, maculate, maculated,
   muddy, murky, patchy, peppered, pocked, pockmarked, pocky,
   pointille, pointillistic, polka-dot, punctated, smirched, smoky,
   smudgy, smutty, sooty, spangled, spattered, specked, speckled,
   speckledy, speckly, splashed, splattered, splotched, splotchy,
   spotted, spotty, sprinkled, stippled, studded