At work yesterday, I noticed that my hand smelt rather unpleasant. It was the sort of smell you get if you've been handling a lot of coins. Not very nice. So I went and washed my hands.
Five minutes later, I noticed that the smell was still there. So I went and washed my hands again—a bit more dilligently this time.
Blow me, when I returned to my desk, the smell was still there! This was getting ridiculous. So I went to wash my hands yet again.
It turned out the smell was from the soap.