The Collaborative International Dictionary of English v.0.48:

Trashy \Trash"y\, a. [Compar. Trashier; superl. Trashiest.]
   Like trash; containing much trash; waste; rejected;
   worthless; useless; as, a trashy novel.
   [1913 Webster]

WordNet (r) 3.0 (2006):

trashy
    adj 1: cheap and inferior; of no value; "rubbishy newspapers
           that form almost the sole reading of the majority";
           "trashy merchandise" [syn: rubbishy, trashy]
    2: tastelessly showy; "a flash car"; "a flashy ring"; "garish
       colors"; "a gaudy costume"; "loud sport shirts"; "a
       meretricious yet stylish book"; "tawdry ornaments" [syn:
       brassy, cheap, flash, flashy, garish, gaudy,
       gimcrack, loud, meretricious, tacky, tatty,
       tawdry, trashy]

Moby Thesaurus II by Grady Ward, 1.0:

63 Moby Thesaurus words for "trashy":
   NG, Pickwickian, absurd, base, beggarly, beneath contempt, cheap,
   cheesy, common, contemptible, crummy, despicable, foolish, gaudy,
   gimcracky, good-for-naught, good-for-nothing, junk, junky, mean,
   meretricious, miserable, no-account, no-good, nonsensical,
   not worth having, not worth mentioning, not worthwhile, nugacious,
   nugatory, paltry, pathetic, pitiable, pitiful, poor, poppycockish,
   rubbishy, sad, scrubby, scruffy, scummy, scurvy, scuzzy, shabby,
   shoddy, silly, skimble-skamble, sleazy, sorry, tatty, third-rate,
   trivial, trumpery, twaddling, twaddly, two-for-a-cent,
   two-for-a-penny, twopenny, twopenny-halfpenny, valueless, vile,
   worthless, wretched