Is theft a problem at your garage sales?
I had some problems with this family that used to come to my garage sales. They would gather up a ton of stuff and the kids (little scheisters) would put the more valuable merchandise inside of other things. I finally caught them doing it when I noticed a few pairs of Versace dress shoes were missing off of my table. Then I found three 35MM cameras and expensive lenses stuffed into jacket pockets. If you have garage sales, be on the lookout. Some of these people will try to rip you off when your back is turned.
On a more positive note: When I was buying several units per week, I didn't have time to go through everything with a fine tooth comb. One day, this guy walked up to my tent holding a small jewelry box and said "you probably didn't want to leave that out there did you?" I opened the box and it had several gold/diamond rings inside. The guy was actually a gold reseller and he made me an offer on the spot.
He could have easily put those rings in the pocket of a pair of blue jeans, given me a couple of dollars and then left without me ever knowing. It's nice to see that there are still some honest people left it the world.