Now that you mention it,I've never seen it taken into account at a shop either.

A friend of mine has a rig where the scale is on a rope over a pulley. The bow is locked in place in the fixture, scale hooked onto the stringand then the rope is pulled. There is a yardstick on the back board that lets you check poundage at different draw lengths. I just assumed a variance between scales when the bow checked different on the shop scale than it does on his.

It's too early in the morning to figure this'n out. [8D]