You know how vending machine sometimes give you an extra drink, well what about if rarely, it just takes your money? Maybe then you could go complain to someone in a building and they'd give you like 10 drinks.
That happens waaaaay too much IRL. Well, at least for me. ): It goes kinda like this for me:
~ Insert Coins
~ SOLD OUT MESSAGE / Internal Error?
~ Presses button for coins back
~ MACHINE DOESN'T GIVE COINS BACK?
It'd be funny if Vending machines work that way in pokemon too. :3