Some guides are very accurate. Nine times out of ten they can judge a ram on the hoof and give an estimate of B&C gross that is within 1.5%. These people are the exception and not the rule. Everyone makes mistakes. Remember what happened on the Kluane in 2008? The auction tag holder in 06 got a 175 inch dall and in 07 they took a 180 ram. So Doug Leech bid $310,000 to hunt in 08. The "team" of guides went in and scouted the area. On opening day they shot the ram they had scouted. The long horn went 40x13. A great trophy... But far from what the guides had judged the ram to be. What most qualitiy guides have going for them is experience in their given areas. Hope that your guide has really spent a lot of time in the sheep country where you will be hunting. It's more important that your guide be able to tell you the quality of a ram with respect to the area you are hunting in rather than its score. Instead of asking your guide to score a ram wouldn't it be better to ask how does this ram compare, bigger/better/older, to other rams in the area? This is when experience with the herd is worth more than the ability to judge inches through a spotting scope. Rather than score I think the goal should be to not have any regrets after you pull the trigger. If you harvest the best ram a given habitat has to offer then there should be no regrets, regardless of inches.