No way to tell for sure but I'd bet it happens more than we know.
Yep, no way to tell, but if it only happens in 1 in 10 or 20, it might be the one you get that is then a bit short of the original goodies.
The thing that I think is funny that one of the auctioneers big in my area makes a big deal of the fact that they (the auctioneer) cut the locks. Well, consider this.
1) the property manager cuts off the original lkr owner lock.
2) the property manager can go in and look, take, whatever.
3) the property manager comes out and puts a lock on.
4) the auctioneer comes along and cuts that lock off....he doesn't know it wasn't the original.
The worst case I have seen of this happened when another regular buyer and I made a point of watching the locks get cut off. This was being done by the property owner AT THE AUCTION, he made a big deal of this.
Guess he didn't realize we were watching carefully. Every lock he cut (10 of them) was of the same brand, quality of construction and the brand he sold in his office. He had been inside on all lockers, come back out and put his locks on after doing who knows what in the lkr.