WordNet sense 1 (inclined to anger or bad feelings with overtones of menace):

surly

WordNet sense 2 (having an irritable and unpleasant disposition):

ill-natured

WordNet sense 3 (morally reprehensible):

despicable, slimy, unworthy, vile, worthless, wretched

WordNet sense 4 (morally bad or wrong):

evil

WordNet sense 5 (unpleasant to look at):

unsightly

WordNet sense 6 (so extremely ugly as to be terrifying):

hideous, repulsive

WordNet sense 7 (distorted and unnatural in shape or size; abnormal and hideous):

grotesque, monstrous

WordNet sense 8 (having an evil appearance):

evil-looking

WordNet sense 9 (provoking horror):

atrocious, frightful, horrible, horrifying

WordNet sense 10 (causing alarm or fear):

alarming