A Caribbean (not Haitian) guy I know always refers to them as the cursed people and apparently it's a pretty common label in most Caribbean nations. (He also refuses to have anything to do with them and said "I only ever met one decent Haitian")
The story goes that the then leader and some of his fellow rebels met in a hill with a Haitian equivalent of a voodoo queen that was possessed by the Devil. Devil says "Give your people over to me and I will free you from the White man." They agree and then immediately drive out the French. Thus, their title as "The Cursed People." He blames that event for all of the ills in Haiti and claims it will never, ever get better, even the ground they walk on is cursed.
He's told me plenty of local stories from his home town about cursed houses/uncuttable trees, a man who was cursed and would chimp out every full moon, black magic Baptists you could pay to curse people, and way more insane stuff that seemed "normal" to him.
Any of it true? I don't know, probably to an extent. I just found it to be an interesting explanation from a guy whose explanation didn't involve race