Green’s Dictionary of Slang

hot-arsed adj.

also hot-ass, hot-assed, hot-bummed, hot-cunted
[hot adj. (1a) + -arsed sfx (2)/-assed sfx (2)/bum n.1 (1)/cunt n. (1)]

1. of a woman, lecherous, lascivious.

Ten Pleasures of Marriage in (DSUE).
Cremorne I 28: The cook, Dolly, is a hot-arsed a bitch as any wench in the county.
[UK]‘Walter’ My Secret Life (1966) II 313: She was getting hot-arsed and she lined the poking. [Ibid.] III 606: I quite longed to see this hot-bummed, cunt-neglected wife [Ibid.] VI 1154: She is such a hot-cunted little devil, that God knows what she’ll be up to.
[US]J. Jones From Here to Eternity (1998) 221: Went on the bum, instead of finding him a good hotassed wench and settlin down.
[US]P. Marshall Brown Girl, Brownstones (1960) 31: ‘You know every Sat’day he does run bird-speed to the concubine.’ [...] Virgie roared her disapproval. ‘Nobody din say he can’t have the hot-ass woman but, c’dear, his own got to come first.’.
[US]D. Dee Golden Betty 9: The close proximity of a hot-assed bitch.
[US]E. Thompson Garden of Sand (1981) 15: What did that hot-assed little bitch know?
[UK]G. Burn Happy Like Murderers 79: Her brother-in-law [...] called her a ‘hot-arsed little sod’.

2. in fig. use, exciting, stimulating.

J.D. Barber Race for the Presidency 161: But John Lindsay views the gaffe scene less sanguinely: ‘Some nice rational guy has a hotassed conversation with the candidate—and rushes off’ [excitedly].