A variety--a 60X stereo scope at work, and a couple of hand-helds in various ranges, none over 60X, with their own lights and other external sources, too. I've been very careful to try all light directions, to highlight any scratching from any direction. The one single thing I'm absolutely sure of is that I'm seeing all there is to see, and every stage in the sharpening process accurately. That's really not the issue. And as I said before, I'm viewing newspaper as a standard, since everyone has access to the same thing, and that's scratching, too.
All of my blades are old ones. Could it possibly be a factor of softer steel? I'm doubting that, but one never knows.