bad, bitter, disagreeable, displeasing, distasteful, harsh, icky, nasty, rotten, sour, uncongenial, unlovely, unpalatable, unpleasing, unsavory, unwelcome, wicked, yucky(also yukky)

abhorrent, abominable, appalling, awful, beastly, bilious, disgusting, dreadful, foul, ghastly, gnarly(slang), god-awful, gross, hateful, hellish, hideous, horrendous, horrible, horrid, invidious, loathsome, nauseating, nauseous, noisome, obnoxious, obscene, odious, offensive, repellent(also repellant), repugnant, repulsive, revolting, revulsive, scandalous, seamy, shocking, sick, sickening, ugly, unholy, vile, villainousaggravating, annoying, galling, irritating, vexingcrappy(slang), cruddy, crummy(also crumby), lousy, miserable, sucky(slang), wretched