Opposite words for classy:
flashy, flamboyant, rough-edged, tacky, uncultivated, inelegant, uncultured, ticky-tacky, dowdy, gaudy, garish, cheesy, unhandsome, unpolished, graceless, loud, rough-hewn, vulgar, crude, splashy, tawdry, glitzy, unrefined, unstylish, unfashionable, tasteless, trashy, uncouth, raffish, styleless, grotesque, coarse, rude.
Usage samples:
  1. No use putting the county to the expense of a trial when Pete has such a classy perjured alibi as I would give him.
    "Somewhere in Red Gap", Harry Leon Wilson.
  2. The coach gasped at the scintillating play, and White called out: Classy stuff, kid, classy stuff.
    "Bert Wilson's Fadeaway Ball", J. W. Duffield.
  3. It's a far cry from Flamm Avenue to where a classy girl like you can land herself if she steers right.
    "Gaslight Sonatas", Fannie Hurst.
  4. In consequence of that fact and perhaps on the condition implied in the term, Mr. Gilfeather was permitted to conduct his high- toned and classy place on a street where he would have no competition.
    "Concerning Sally", William John Hopkins.