just one opinion

if you happen to get thirsty at work, and you happen to put a dollar bill in the vending machine, and it happens to be out of any other beverage that you like, and it happens to refuse to return your dollar, and the only available drink happens to be coke zero, and you happen to press that button, and it happens to vend you that coke zero, you might as well just toss it out and write off that dollar rather than subject yourself to coke zero's miserable aftertaste.... gah!