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. [late 17C+] of a woman, lecherous, lascivious.

2. [1970s] in fig. use, exciting, stimulating.