pet peeve: "good intentions".
if the intentions consistently cause bad things, then they just aren't very good. yeah, it's based on bad reasoning/understanding. it always is, that's how evil happens.
how else are these intentions supposed to be "good"? by making people feel good about themselves?
even people who think they "do evil on purpose" are just semantically confused. they still act according to their own values. though their confusion probably doesn't help with having good ones.