Apparently, the bottles were electronically tagged

Dependent upon how modern they are, some mini-bars have sensors underneath the individual slots which the bottles stand on.If an item is removed the electronic circuitry automatically charges the item to the bill for the room.If you have access to more than one room, you will see that the mini-bars are identically stocked with the individual items - tonic water/miniature whisky etc in identical positions in the bars.

The moral of this story is, of course, sod the haggis - you can always get one at the airport (unless you run over one on the way !!)