I've gotten some great deals in my local pawn shops. The best ones are those attached to some chain, NOT the ones owned by an independent. The independents usually know alot more about what they are selling and set their prices accordingly. The chains usually don't know quite as much and this means there is alot more opportunity to get a really good deal. Personally I got several hundred dollars worth of Proto wrenches (1 1/2 to like 2 1/2), along with a handfull of smaller wrenches once for $100. Had them marked for like $120 and I walked away and went back several hours later and made them an offer, which they accepted. I also got a $2000 plus IR impact for around $200, along with quite a few other real deals. The thing is to know what you are looking at and never pay what they are asking unless you know for a fact that you are already all but stealing it for the asking price.
A week or so back Dad was in one and went against habit and looked inside a cheap toolbox. Typically cheap, junky boxes are full of cheap, junky tools. This one turned out to be filled with older name brand tools like Snap-On, MAC, S-K, etc, etc. He wound up getting the whole box for something like $175. When he got home he began checking prices and just one of the S-K sets in the box was worth just shy of what he paid for the whole thing.
As far as stolen items, I'm sure there are some that get through and get resold, just like anywhere else in the world. Thing is they do everything they can to identify the folks doing the pawning and insure that the items aren't stolen. I've been in severl when the police would come in and take a look around, and once even saw them find an antique musical instrument stolen from the Charlotte Symphony Orchestra. The bad thing about something like that is the shop loses the money they paid out for the item, and nobody likes to lose money.
On another note, they often make good money reselling items. I was in one shop years ago when a guy brought in a piece of stereo equipment he had bought a few weeks before from that shop. Thing still had a price tag on it for something like $50. The guy sold it back to them for around $15. I guarantee you it was back on the shelf for $50 before I got home that evening.