He got fucked a couple times when he first started. But he always says that as you gain more experience with this stuff you can just kind of tell which unit has good shit and which doesn't based on the type of furniture you can see, which is all you can really see from the outside of one of these units anyways.
He's come up on some really cool shit though. Probably about 50 different pieces of antique furniture, a comic collection that he sold to a collector for a couple grand, a couple flat screens that were tucked in the back of the unit and easily covered twice what he paid for everything, some autographed sports memorabilia and a lot of old books. The books aren't worth much, but he's started collecting rare editions and that sort of thing and collectively they are worth much more than they are individually. So there's always the possibility you find shit that interests you personally, along with stuff that can make you money.