Only once. One evening, I was not feeling well and decided to have some buttered toast and tea while I watched some television. I had just had new carpet installed about a week before. Somehow, I caught my toe and the toast flew off the plate and, of course, landed buttered side down. I tried to clean it with Folex and that took the color out of the carpet. So, I lived with an ugly spot until I sold the house. I just didn't have the heart to have all of the furniture moved and the carpet replaced again.
My current house has all hard surface flooring.