I have read several times where people have talked about there scales not being accurate. I felt it may be helpfull to mention that it is easy to check. I was concerned about this last spring so I simply took some steel weights and weighed them on the bathroom scales and they were what they were marked so I hung them on the bow scale and found to my surprise that my scale was fairly accurate.
Be sure to check it over the full range. 30, 40, 50, 60, and so on.