@ David: knot stains showing through the paint. They've been there for years, and somehow I just don't notice them. And yet they are obvious to anyone with a fresh set of eyes.
Thanks to all for commenting. Sometimes you "see" a scene and you think, "wow, that's nice". Then there's the little trick in transferring the vision to something you can capture and show. And then even when you do capture, you realize that the emotional context is hard to reproduce (you were there, your viewers weren't). But that is good training, for this exercise reminds me that visually the image must stand on its own.