I was hoping somebody could name this one. As a child, an irresponsible adult I knew sometimes let me watch horror films. The ones I remember best are The Thing, Prom Night 2 (I think), and a third film that I simply cannot track down. The only scene I recall from this movie involved the main antagonist, a sexy lady monster, in a hot tub making out with a curly-haired guy. A monster hunter is after her, apparently, and she knows it. So at the, ahem, moment of truth, she morphs into a hideous monster with lots of mouths all over her body (that’s what my five-year-old self interpreted them as, anyway…) and kills the guy. The monster hunter shows up and finds the guy’s corpse in a hot tub full of blood. This would have been mid- or late-80s. It definitely wasn’t Species, although there are more than a few similarities.
Thanks for the help!