They have no excuse at that point. Being exposed to the most horrendous retail system of ALL time, I know the ins and outs of retail software and they're all the same. If the UPC is corrupt or smeared the laser can't pick it up. So how do average cashiers (who don't give two hoots about their job) do? Scan it, again and again and again. FOOL! Type the numbers by hand or feel my wrath.