Throughout his history, Etrigan has always been portrayed as a pretty mean dude. He hasn't shyed away from savage killing, sadism, masochism, torturing even of his own brother, threatning to eat people, and even being so damn dangerous the higher ups in Hell need him to be controlled because of his unpredictability. But has there ever been things that even the rhyming demon says is low and dirty? Only once have I seen such a thing, and that was where he showed disdain for rapists.
Everyone has morals of some sort, even if they're not morals that anyone else would agree with.
If you had absolutely zero morals then you'd essentially have no impulse control to any degree and wouldn't even be a character, you'd just be a directionless tornado.