I doubth very seriously that the place where the auctions are taking place has no clue about what's in those lockers. There is no way that t hey are going to just let valuable items be auctioned off. I also read that the items that the players find in the lockers and take to be 'looked at' actually come from that store/place.
Also, if you have any valuable items in your storage unit, why in the hell wouldn't you get it out and sell it ?
'Oh! here's a painting valued at $5,000 but it's just left in this unit because the renter couldn't pay the storage fee. WTFever!!!