Almost everyone has it but it's such a pain in the behind to clean. I found a way to clean it and it's really easy. Woolite Carpet Cleaner. It comes in a spray can and it's prefect for making the straight lines for the grout. You just let it sit for about 10 minutes and mop clean. I have ceramic tile and a off-white and gray color of grout and it comes clean. On one website I saw it doesn't always work on different colors or certain seals of grout though.