Ummm.... I only clean ones I think are dirty (either they are visibly dirty or used ones).
By the way, that Macintosh ADB keyboard had a strange mechanism on it, and I know space bars are hard, but that one's the only one that gives me lots of trouble. Sometime, take the space bar off of at least one non apple keyboard, then take the space bar off one ADB's. I promise you can tell the difference.
P.S. I only clean equipment that is in my possession, or in some cases in our basement computer lab, spare dirty keyboards. I won't clean anyone else's keyboards unless they specifically request. And out of 3 keyboards, I only lost 1 keycap. That's what percentage? Besides, you don't even like that ADB anyway.