f/22, ISO 80, macro focus, blank white wall
If I had not read these threads and done this controlled, artificial test, I would have never seen them.
I've been busy poring over my previous photos, taken at f/11 (even one at f/14) against a pure blue sky at infinity focus, and I am completely unable to see them, even though I know exactly where to look. They are quite simply less distinct than
sensor noise at ISO 100 under those conditions. At any higher ISO, I can confidently say that they are literally impossible to distinguish against sensor noise. Therefore I conclude that they are completely irrelevant to me in real world shots.
Unfortunately, now that I know, I'm going to be a little paranoid, even though I know they will never be seen in any real photo I shoot. Sometimes ignorance is bliss.