Rick, one of the owners, says that he has a lot of experience in coins, but I'm not sure that's true. He may have had experience buying and selling the kind of stuff that might come into a pawn shop, but he's definitely not a numismatist as his lack of real knowledge shows through now and then.
However, he's certainly more knowledgable than the average person of the street. There was an episode where I was sure he was clueless: he told an employee that Standing Liberty Quarters were very rare and worth $1,000.00 each. It turned out that he knows better and was trying to teach a lesson.
Rick does sometimes seem to be out of his depth. On the other hand, trying to judge the value of something from a brief glimpse on a television screen is obviously not ideal.
Many people have said that these shows are scripted. According to people who have actually been on the show, that's not entirely true. Apparently the negotiations are unscripted, though some coaching does take place (see the post by The Penny Lady here).
Like any pawn shop, bad things can happen with stolen coins: "'Pawn Stars' shop apparently melts down stolen coin collection"
If yo've never seen the show, this 2 minute clip will give you an idea of what happens.
Note: All my coins are in a safe deposit box. I keep nothing in my home.
Contests and giveaways: http://coins.aplawrence.com/2014/05/contests-and-giveaways.html