WordNet (r) 3.0 (2006):

shitty
    adj 1: very bad; "a lousy play"; "it's a stinking world" [syn:
           icky, crappy, lousy, rotten, shitty,
           stinking, stinky]

Moby Thesaurus II by Grady Ward, 1.0:

60 Moby Thesaurus words for "shitty":
   barfy, bum, cheesy, crappy, creepy, crummy, dirty, disgusting,
   dungy, excremental, excrementary, fecal, feculent, fetid, filthy,
   flyblown, foul, gloppy, godawful, goshawful, grim, gunky, hairy,
   icky, maggoty, malodorous, mephitic, mucky, nasty, nauseating,
   odious, ordurous, puky, punk, putrid, rank, repulsive, rotten,
   scabby, scatologic, scatological, scummy, scurfy, slabby, slimy,
   sloppy, sloshy, sludgy, slushy, sposhy, stercoraceous, stercoral,
   stinking, stinky, urinary, urinative, vile, vomity, wormy,
   yecchy