Green’s Dictionary of Slang

(US) immoral.

1926		‘breach of promise case’ in Canfield Coll. He seduced the plaintiff under a promise of marriage. He is a miserable and breachy coon who merits condign punishment.
1929		A.E. Perkins ‘More Notes on Maine Dialect’ in AS V:2 123: The word ‘breechy’ was sometimes applied to a woman who was immoral and ‘jumped the pasture fence.’.
1949		PADS 11 18: Breachy [...] Lecherous.