Once upon a time, my husband replaced a lightbulb above my kitchen sink. I'm not even sure how long it had been out, but the replacement of said bulb was very... illuminating.
We have a white cast iron sink. It's lovely. It's lovely in the dark. It was quite frightening in the light. Don't worry, Dear Reader, Comet cleaned it right up. What Comet couldn't handle, an Oxygen Bleach (not Oxiclean, but the same stuff) soak took care of.
I like powdered Comet. My mom used it. I use it. I bought it on sale with a coupon at Walgreens a few weeks ago... a small can for only 50 cents. I put one can under the sink in my bathroom, one can under the sink in my kitchen. And when I grow up and get a bigger house, there will be a can of Comet near every sink and every toilet. My children will know how to use it. My sinks and toilets shall shine in the light.
The moral of the story is: don't replace burned out light bulbs.