WordNet (r) 3.0 (2006):

ratty
    adj 1: of or characteristic of rats
    2: showing signs of wear and tear; "a ratty old overcoat";
       "shabby furniture"; "an old house with dirty windows and
       tatty curtains" [syn: moth-eaten, ratty, shabby,
       tatty]
    3: dirty and infested with rats

Moby Thesaurus II by Grady Ward, 1.0:

56 Moby Thesaurus words for "ratty":
   angry, annoyed, beset, choleric, crabbed, cranky, cross, dirty,
   disagreeable, dowdy, down-at-heel, down-at-the-heels, frayed,
   frazzled, full of holes, greasy, grubby, holey, impatient, in rags,
   in shreds, in tatters, infested, irritable, irritated, lousy,
   matted, mouselike, mousy, patchy, pedicular, pediculous, peppery,
   plagued, ragged, raggedy, ravaged, rodent, rodential, scruffy,
   seedy, shabby, shoddy, short-tempered, straggly, tacky, tattered,
   tatty, teeming, testy, tetchy, torn, touchy, unkempt, verminous,
   wormy