I'm sure that most (if not all) of us have at some point in our lives been the victim of well-intentioned behavior, and most (if not all) have ourselves acted misguidedly with the best of intentions. But it's a lot easier to see where others went wrong than to admit our own mistakes, isn't it?
Take, for instance, parents, since they're the easiest example. Most people, by the time they reach adulthood, are no longer under the illusion (if they ever were) that their parents are perfect. But a lot of parents I've encountered (and I've encountered quite a few) seem to think that, while they might not have been perfect, they sure made a lot fewer mistakes than average. And, of course, if their children didn't turn out perfect and/or the way they were "supposed to", well, it's certainly not their fault, because after all, "we did our best." But I would disagree with them there, because while they might have meant their best (and I do think that most parents, with a few exceptions, really do mean to act in the best interests of their children) I would say that sometimes having good intentions just isn't enough. Meaning well and doing well are two entirely different things. Someone can mean well and do horribly.
Another thing I see a lot of is people taking credit for the result because the result was their intention, without taking into account all of the other factors which led to it. This one I also see a lot of from parents, who tend to think that if their children turned out well that it must be because of them. However, in my experience and completely unprofessional opinion, a lot of children turn out well in spite of their parents, not because of. (This is usually judged by how much more messed up I would be if I had other people's parents--it makes me appreciate my own.) For instance, my parents take a lot of credit for how the Sibs and I turned out. And while dear Ma and Pa do deserve at least some of it (because like I said, I'm learning to appreciate my parents more), they completely ignore two things: 1) There are a LOT of people/experiences that have strongly influenced who I became as a person over which they had little or no control. 2) A number of the issues with which I still struggle today stem straight back to them and how they raised me. Granted, they're probably next to unaware of #2, because I've worked very hard at keeping them unaware of that, but they should at least be cognizant of #1. It's just funny for me me when I hear my mother tell me how wonderfully well-adjusted I turned out, blah, blah, blah...and I'm thinking, "Wow...she has no idea, does she?"
Still, as someone who has herself also made well-intentioned mistakes (or sometimes, grievous errors), I know how hard it is to admit to oneself, let alone others, that while one's intentions may have been well-placed, one's actions have gone miserably wrong. I think that's how children learn to forgive their parents (at least most of the time)--we know they meant well, and if they messed up anyway...well, at least they meant well. Of course, it's not only parentsI have to forgive, but all the people I know. Because as hurt as I may be (or may have been), if I know that the intentions were good, I have to find it in me to forgive others, because I would want others to forgive me.