The minibar is an evolutionary oddity. Like the coelacanth or dodo, it is a relic of a bygone era which served an important role in its time. However, upon finding one in your hotel room, it is immediately treated with suspicion.
Depending on who you ask, the mini-bar was possibly a piece of German engineering imported from Siegerland for American convenience to The Chicago Madison Hotel in the mid 1960s.
Or a ruthlessly compressed piece of Canton hospitality created for the Hong Kong Hilton around the same time.
Either way it was a mid-twentieth century invention to minimise space and labour costs while maximising the profit made on in-room drink sales.
While the bars remained small the bills began to grow.
At some point during the last few decades the economics of the mini bar changed. Public opinion was that this in-room-honey-trap was not to be trusted.
It's a source of low-key anxiety in the hotels which still include mini-bars.
There's the feeling that breaking the cap on a miniature bottle of wine will leave you and your family destitute and in a debtors' prison.
The minibar has been used to vend some outrageous items. Toronto's Drake Hotel has gained notoriety for quirky in-room charges such as $60 hemp candles and a seriously NSFW, $460 gold-plated pleasure pack.
Trump Towers famously boasted a "water-library" (whatever that means) billing $45 a bottle.
The most expensive item ever included in a minibar service might be a bottle of Louis XIII Grand Champagne Cognac at the Intercontinental Amsterdam, priced at 3500 euros or about $6000. Blogger John Ollila shared the mindboggling find to the website Loyalty Lobby. With a 70 per cent markup on the 2000 euro price from Remy Martin, it appears even the highest-end hotels are not free of minibar markup.
According to stockists even the word 'complimentary' doesn't massively increase minibar consumption. The distrust of mini-bars is such that people hardly touch them when they're free.
In spite of this, according to Accor hotels, the top selling item from the host of tiny temptations is bottled water. Not scotch, not chips, not even the miniaturised peanut slab - just water.
Although the same study suggested this might have something to do with the bottled water being placed closer to the bed than the taps.
And yet somehow the in-room bars are still loss-making. Many hotels have removed the convenience-era relics saying that it's impossible to make a profit from the in-room stocks.
Perhaps because guests are gaming the system.
"I'd clear out the snacks and beverages by the end of a week at conference. Just take a photo, keep a list and hit the CVS before you leave," was one hotel guest's tip.
Less honest mini-bar hacks include watering down the vodka miniatures with tap water.
Even honest re-stockists will discover, these tricks could backfire.
As one family discovered during a stay at the Hilton DoubleTree in Chicago, after they were charged $80 for merely opening the fridge door.
"A small number of our hotels have units that use motion-sensor technology, and should include information on the menu card or unit stating the way in which the sensors work," a spokesperson for the hotel told the Tribune at the time.
As many as 90 per cent of these automated mini-bar charges could be by mistake, they said.