In her Nerve advice column, Kate Sullivan discusses proper sexual etiquette during a bedbug infestation, like whether or not you're obliged to tell a one-night stand. (Answer: "Only if you're serious. If not, just have sex in the kitchen.")
How the hell is it so hard to say "We can't go back to my place. My roommate is psychotic."
Hell, I whipped that one out when I didn't want someone to know where I lived and/or just hadn't cleaned recently. No one ever questions it.
My poor roommate was actually a lovely person.