Originally Posted by BBear 
I have a general question about how this debug mode works:
do you adjust the AF for each lens or do you adjust for the body?
I think it is for the lens, but if so, does the camera memorize the lens you are adjusting for? And it is for the VERY specific lens (serial number) or for any same-model lens?
The adjustment on the K10D is for the body and it effects all lenses. For the K20D it is for the same-model lens, it uses the transmitted lens-id which is also stored in EXIF information.
I adjusted my K10: first at +70 for my FA77, now at +100 because my 18-250 needed a bit more. The good news is that eg my Tokina 400 did focus correctly and still does, so it does effect each lens in a different way.
It is highly likely that if you discover backfocussing with a lens, others are also backfocussing, but that you didn't notice it. An Fa77/1.8 will show focus problems much more clearly than a 12-24 or 18-55 kit lens, because of the very shallow depth-of-field of the 77.