You have to be careful and learn the ropes of the area. Here are my examples:
1) local manager - told me the regional boss has him combine units sometimes to clean them out. So you get furniture from one tossed in to another. They don't go through the units that I can tell. Mostly trying to clean out units cheaply. You can sort of tell when they do that or when they do the unit looks even more trashy and gets low or no bids.
2) Caravan auction - one of the local managers will combine units. We are all just carefull to look for it. Gotten 3 different people stuff out of 1 unit before. Person that bought the unit still made money (jewelry) so it don't seem like they toss the units first but you never know.
3) Caravan auction - the manager / auctioneer lets people go in the unit. Still can't open totes, boxes, or such but we can look behind the furniture and things. If unit is full we can still only look from the door but is still different. Really does this on the large units that are only 1/3 full but all you see is the matress in front.
4) Few other units at different places have looked "staged" to me. May or may not be the case but if I think that I bid about 2/3 my max or lower.
Yet a different caravan I found out when they cut the locks and what all they do. On friday after 5:30 if people don't pay up they cut the locks, take a picture with a sign showing date/unit #, then close and put their lock on for Sat auction.
Start getting to know the local staff at each facility and you can learn alot. It's how I found out about #1. I was chatting up the local guy after the big boss left. He was telling me about another unit he had that didn't come up for auction but needed to be cleaned out. So I ended up cleaning out a 0 bid locker, my 2 lockers, and got to cherry pick what wanted out of a 4th. All I had to do was toss the matress and boxspring in their dumpster. Found 2 computers to scrap in the trash at same time. Now I make it a habit of stopping in to chat once every other week. So I may find out what units have been combined if any or find more free goodies.
I've learned only 1 place is truely crooked and I stay away from them (staged units, person in crowd running bid up, etc). Most of the places so far seem legit, or I've never heard or seen anything really fishy. The other few places like above you just have to watch the units. They don't seem to be pulling stuff out of them as much as giving you extra trash to haul off. Still not cool in my book but that's life.