The Collaborative International Dictionary of English v.0.48:

Mussy \Muss"y\, a. [From 2d Muss.]
   Disarranged; rumpled. [Colloq. U.S.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

mussy
    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:

44 Moby Thesaurus words for "mussy":
   beat-up, bedraggled, blowzy, careless, chintzy, dilapidated,
   disheveled, drabbletailed, draggled, draggletailed, frowzy,
   frumpish, frumpy, grubby, in rags, informal, loose, lumpen, messy,
   negligent, poky, ragged, raggedy, ruinous, scraggly, seedy, shabby,
   shoddy, slack, slatternly, slipshod, slobbery, sloppy, sloven,
   slovenly, sluttish, sordid, squalid, tacky, tattered, unkempt,
   unneat, unsightly, untidy