Don't check out late
My wife was going to check out while I was at a conference. She got hung up in traffic and was an hour late for checkout (our fault). When she arrived; staff had thrown away our groceries; except for the full bottle of Grey Goose vodka, which they kept for themselves. Our belongings were in Lost in Found (some of them; still missing phone chargers). 
Room smelled like someone had thrown up in it prior to our arrival; and most likely they had. There were peanut M&Ms around the edges of the room, under the curtains and furniture. Unknown substance smeared across face of mini-fridge.