Intelligence is a factor in Clerks in Pawn Stars: The Game. It determines how much the bonus meter fills up. The clerk with the highest intelligence is Rick (having an intelligence rating of 100%) while the lowest is Ciona the Wench (a pitiful 2%).
A good addition to one's pawn shop would be the Refridgerator, increasing the amount of the intelligence of the chosen clerk by 10%, a nice deal considering the mere $25,000 in game price.