The last place you would think to look.
So recently we had some bright guests who seemed to be a bit worried about leaving their wallet in the room. All the rooms have safes and they are free and easy enough to use, however this couple apparently didn't trust them and decided to leave their wallet in a safer place, the rubbish bin. However the cleaners had been in and emptied the rubbish, they then came down to reception to complain that they had their wallet taken (I wasn't there to see the look on their faces and deal with them unfortunately) the husband had left the wallet in the bin and it had €500 in it, the wife was apparently furious. Since we didn't want anyone rummaging around in the bins in case something happens, we just said the bin lorries had been already and that it was lost forever. Let that be a lesson to everyone, no leaving valuables in the bin lol. Some people learn common sense the hard way.