Don't kid yourself, bad guys will open carry as well. How would anyone tell the difference between the good or bad guy? They'll blend right in with the rest of the crowd.
And in a situation when nobody is OCing and the criminals hide their weapons, they stand out from the law-abiding CCWer how exactly?
It seems that either case, the criminal has a weapon, and still blends in with the rest of the crowd.
Though I have a sneaking suspicion that people with felonies might have less inclination to display their guns for the world to see than one who is legally cleared to do so.