Sometimes an answer is just plain wrong. If there is no grey area and I allow the answer to stand without comment, I feel as though I'm a party to disseminating misinformation. Just downvoting doesn't always feel like enough, especially when there are already upvotes (I hate it when I see that).
When I comment on such answers I'm trying to help the answerer understand, so I will be as gentle as I know how to be. I don't want to be in any way discouraging. It's equally important (perhaps more so) to reign in the answer. People come here to learn. If a teacher tells a second grader that there are 12 ounces in a pound, that's potentially damaging. It's important to purge that wrong information ASAP from the child's mind. Yet here, learners answer questions posed by other learners. It's potentially discouraging to say, "That answer is incorrect", but it has to be done.
Recently I had this come up repeatedly in the course of just a few minutes. I looked at new answers to active questions and one was absolutely wrong. So I corrected the answer in comments. As it turns out, the person who wrote the answer was here. We had a back and forth in comments which we moved to chat. It took a long time to get through (thank you, you who know who you are), but I felt good about how we left things. Then I went back to active questions. Sure enough, right at the top of the board were a few poor answers and at least one wrong answer from the same person. Had I commented on every one of those answers, the guy would have (understandably) felt persecuted. Even worse, that perceived persecution would have been coming from a relative newbie here, the person I wanted to correct (repeatedly) has 10X my rep points.
I ended up just leaving my computer for the night, which felt like a rather selfish way to handle it. Does anybody have advice for me?