As a psychotherapist, I know that kind of talk is unhelpful at best, and damaging at worst, and yet I still fall victim to it. Because we all do. And it takes work to change it. But it's worth it. Healthy self-appraisal is associated with reduced depression and anxiety, more satisfying relationships, and improved overall quality of life.
Sometimes things just don't come out the way we mean them to. Okay. That's an understatement. Sometimes we just plain say sh*t to our kids that we shouldn't! As I see it, we may get lots of support and generally do a pretty fabulous job of keeping our feelings in check and our parenting on track, but at some point we're all going to blow it.