Some people online wondered why our lead character, who could have it, didn't just have sex consensually instead.

But, besides it being hurtful, wrong and unacceptable of course, even in this overall silly C-grade 50s black comedy, besides it being a film and that this was how it was written and intended, her character was meant to be an uncivilized sociopath who somehow got off and enjoyed hurting other people, hence why she decided to do that as well. And since she was into killing of innocent people too, and that wasn't considered over the top for her either, it may be frustrating, but its not a total surprise and stretch of the imagination that she also decided to use sex as a weapon no matter how much of it if she wanted it she could have consensually with little problem.

This is explanation, not justification, as an answer to one of the reviews that was written posing such a question.