The Collaborative International Dictionary of English v.0.48:

icky \icky\ adj.
   1. very bad; repulsive; unpleasant; distasteful. [informal]
      [WordNet sense 1]

   Syn: crappy, lousy, rotten, shitty, stinking, stinky.
        [WordNet 1.5]

   2. sticky; as, icky, sticky goo. [WordNet sense 2]

   Syn: gooey.
        [WordNet 1.5]

   3. Overly sentimental; -- of stories or dramas.
      [PJC]

WordNet (r) 3.0 (2006):

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

Moby Thesaurus II by Grady Ward, 1.0:

74 Moby Thesaurus words for "icky":
   bad, barfy, brackish, bum, cheesy, cloying, crappy, creepy, crummy,
   dirty, disgusting, fecal, feculent, fetid, filthy, flyblown, foul,
   fulsome, gloppy, godawful, goshawful, grim, gunky, hairy, high,
   horrible, loathsome, maggoty, malodorous, mawkish, mephitic, mucky,
   nasty, nauseant, nauseating, nauseous, noisome, noxious, odious,
   offensive, ordurous, overripe, poisonous, puky, punk, putrid,
   rancid, rank, rebarbative, repellent, repulsive, revolting, rotten,
   scabby, scummy, scurfy, shitty, sickening, slabby, slimy, sloppy,
   sloshy, sludgy, slushy, spoiled, sposhy, stinking, stinky, vile,
   vomity, weevily, wormy, yecchy, yucky