Candles and Coffee
I remember a few years ago, I was in a candle store looking at candels. Most of them were scented, and after a while...I couldn't smell any of them. The owner of the store recognized my dilemma, and with a smile on her face she came over with a can of ground coffee. She held the can up to me and told me to take a big whiff. The smell of the coffee was so totally different than the perfumed smells of the candles that my smell sence "reset". After that I was able to smell the candles again.
Looking around the store, I wondered how many shoppers couldn't smell them anymore. How many went by appearance alone...how many only looked at the pricetags?