Once at the LeMeridien (now JW Marriott) New Orleans, I was given my key and when I entered the room - a couple was going at it and said whoa! Fortunately it was one of the corner rooms and you can't see the bed when you first open the door.
I was top tier with Meridien's program at that time (wasn't part of Starwood) and was always pre-assigned a nice corner room on an upper floor with a view.
Turns out this was really my room, and the desk had given a key to Mrs. XXX, which had the same last name that I did. Now who was Mrs. XXX in the room with in the middle of the day?
I got reassigned and the room wasn't as good as the one that had been pre-assigned to me and given to Mrs. XXX for devious acts.