Green’s Dictionary of Slang

crooked, morally ambiguous.

1805		T.G. Fessenden Democracy Unveiled 184: Fanatic preachers [...] Whose piety, so dark and mystical, / Is Godward zealous, manward – twistical.
1815		D. Humphreys Yankey in England 43: He may be a straight going crittur, farzino, manwards; but in his dealings with t’other sex, he is a leetle twistical, according to their tell.
1824		R.B. Peake Americans Abroad I i: You are but an underlin’, tho’ you are so uppish and twistical.
1848		Bartlett Dict. Americanisms.
1855		‘Philip Paxton’ Captain Priest 233: He was rather twistical or so [DA].
1870		New Englander June in Schele De Vere (1872) 645: I wouldn’t go deep into that matter, Sam is rayther twistical, and it’s pretty hard, I hearn tell, to get along with him smoothly.
1883		Remin. Rev. George Allen 69: Godward he is a very good man, but manward he’s rather twistical! [DA].