Green’s Dictionary of Slang

(US) depressing, depressed, miserable.

1961		R. Gover One Hundred Dollar Misunderstanding 122: All that sadass big-word noise I gotta lissen to.
1964		J. Baldwin Blues for Mister Charlie 156: You can’t eat because none of your sad-assed chicks can cook.
1974		(con. 1940s) E. Thompson Tattoo (1977) 132: The sadass comic he had seen in the passageway. [Ibid.] 461: They’re getting worried and sadass like everyone else.
1982		W. Wharton Midnight Clear 161: Those poor sad-assed Germans.
2011		D.R. Pollock Devil All the Time 185: She’d come home drunk the night before in one of her sad-ass moods.