WordNet (r) 3.0 (2006):

messy
    adj 1: dirty and disorderly; "a mussy fussy bedroom"; "a child's
           messy eating habits" [syn: messy, mussy]

Moby Thesaurus II by Grady Ward, 1.0:

71 Moby Thesaurus words for "messy":
   beat-up, bedraggled, blowzy, botched, bungling, careless, chintzy,
   clumsy, deficient, dilapidated, dingy, dirty, disheveled,
   drabbletailed, draggled, draggletailed, dusty, frowzy, frumpish,
   frumpy, grimy, grubby, grungy, half-assed, haphazard, hit-and-miss,
   hit-or-miss, in rags, informal, loose, lumpen, miry, muddy, mussy,
   negligent, poky, promiscuous, ragged, raggedy, raunchy, ruinous,
   scraggly, scruffy, seedy, shabby, shoddy, slack, slapdash,
   slatternly, slipshod, slipshoddy, sloppy, slovenly, sluttish,
   smirchy, smoky, smudgy, smutchy, smutty, snuffy, sooty, sordid,
   squalid, tacky, tattered, unfastidious, unkempt, unneat, unsightly,
   unthorough, untidy