I was recently the target of some bad-mouthing. In typical adult manner, this wasn’t done to my face, but, also in typical manner, it eventually reached me. The colleague, a friend, who felt she should tell me was quite apologetic, while I must admit I felt nothing. All I could say to her was “Consider the source”. The source was known for such antics, usually baseless and usually in disproportionate reaction to something or the other. She was so well known for this that she puts the boy who cried wolf to shame.
Which made me realize that: if a hollow tree falls in the woods, and there actually was someone around to hear it, it still makes no sound.