When you put money in those spiral-powered vending machines you’re not buying candy, so much as you are gambling for the chance of getting candy. Sometimes it pays out, sometimes it doesn’t, sometimes it pays out particularly well. The odds are good anyway, compared to slot-machines.
At the Amazon warehouse I was particularly good at shaking loose refreshments that were barely being held by the mighty spirals. Usually I only attempted this when the machine hadn’t paid out on my coins, though there were others who would periodically shake it down just to see what they could get. It was my opinion that the spirals should have been rotated an extra 45 degrees to increase the machine’s reliability.
Years ago, at another job, there was one Coke machine that would often offer up 2 cans if you hit the button twice quickly. I was pretty good at getting the second can and would always give it to whoever else was in the break room.
Once while waiting for someone in the lobby of a hostel in Amsterdam. I put a guilder into a machine, and selected my candy, the spiral rotated, and the package didn’t drop. I restrained myself, thinking it would be fairly ugly-American to beat up on a Dutch vending machine. I went back to my seat and waited for my friend, sulking.