"Usually because no restaurant ever has cleaned out the ice machine. It also depends on what they use to scoop the ice out of the machines. If you got people with dirty hands with a scoop scooping out ice you can imagine all the nasty particles that rub off on the ice etc. Do that 4-5 times a day and you see the potential for nasty to accumulate."
Man, in Africa people are eating fly-burgers. Who cares, it's just a head-thing.