Green’s Dictionary of Slang

1. extremely bad.

[1896		F. Hutcheson Barkeep Stories 191: ‘I close up bot’ his eyes an’, on de level, I give dat guy a scand’lous beatin’’].
1918		J.N. Hall High Adventure 58: ‘You’ll find it pretty rotten when you go over the woods. The air currents there are something scandalous!’.
1985		T.R. Houser Central Sl. 46: scandalous, actin To scheme-on for the purpose of raw dogging. [...] Any outrageous behavior.
1991		L. Bing Do or Die (1992) 17: That is scandalous. Scandalous! [...] Ninety niggers? That’s fucked up.
1997		G. Sikes 8 Ball Chicks (1998) 32: Gang lexicon reserves the word ‘scandalous’ for the most amoral act.
2002		J. Lerner You Got Nothing Coming 13: ‘Parole in Nevada is a trick bag, bro! They violating motherfuckers from the jump, all bogus shit’ [...] ‘It’s scandalous, dawg!’.
2012		‘Dutch’ ? (Pronounced Que) [ebook] Nikki winked at Shameeq, knowing she was doing her job. He smiled back, but he was thinking, Scandalous bitch.

2. excellent, first-rate [on bad = good model].

1992		Bentley & Corbett Prison Sl. 33: Scandalous A compliment of one’s skill or ability. An inmate who is extremely adept at something is said to be scandalous.
2000		W. Shaw Westsiders 55: There’s some scandalous bitches out there.