An intention to good that results in bad is how you detect true evil?
Yes, exactly. What do you think the 9/11 hijackers thought they were doing? People don't kill themselves for evil; they kill themselves because they think they're doing the right thing.
Evil does exist; you see it any time you meet a person who's so convinced that they're in the right that they have no room for doubt, and that there's no price they won't pay to achieve what they think is "right."
But I wonder, what do you call an intention to bad that results in bad?
"Selfish."
Or better yet, an intention to bad that results in good?
"Accident."