Backstab seems to take the most diplo hits, but exact number might vary from civ to civ's flavor.
I've been using some diplo mod for a few games, which shows exact number of how much + or - you get for each modifier (doesn't change diplomacy system, just shows extra info). Same modifier never shows the same number on different civs. My guess is their flavor.
eg: with some civs, you get -25 modifier for competing for same CS. With others, you get -15, with third, you get -5. For warmongering, flavor "tolerate\dislike\hate" also weights differently... so not every civ will equally hate you, even if they declare you a warmonger.
I've been using some diplo mod for a few games, which shows exact number of how much + or - you get for each modifier (doesn't change diplomacy system, just shows extra info). Same modifier never shows the same number on different civs. My guess is their flavor.
eg: with some civs, you get -25 modifier for competing for same CS. With others, you get -15, with third, you get -5. For warmongering, flavor "tolerate\dislike\hate" also weights differently... so not every civ will equally hate you, even if they declare you a warmonger.