IME, all it takes is a shift change, a guest to walk in with a special request and an accommodating FD clerk and poof, there goes your upgrade, special room or specific room number that was promised. For whatever reason, someone standing at the desk is going to get more accommodation than those who arrange over the phone or arrive later unless the phone agent takes extraordinary steps to mark the record as in **DO NOT MOVE**. Not right, but its the way of world.

For years, I used to stay weeks at a time in a certain hotel and desired a specific (ordinary) room and got friendly with the rooms controller to make that happen. The GM said he was going to put a plaque on the door with my name on it.