Spots can return due to any of the following scenarios: Wicking When the carpet is wet, any stains that were more stubborn to remove or hidden will come to the surface as the carpet dries (usually appear in 24 hours). We will re-clean spots that come back in 24 hours. Sometimes it may take a couple times to completely remove the spot through cleaning and if unable to be removed, it is considered a stain and cannot be removed by cleaning. Rapid Resoiling soil or stains come back in ingress and egress areas over the period of a week or more. Most prominent in walk off areas from elevators, kitchens and entrances. Prevented by placing walk off mat in these areas to minimize the soil depositing in these areas. This is the only way to prevent rapid resoiling other than weekly carpet cleaning. Traffic Lane Gray It isn’t just soiling or staining that makes carpets begin to discolor. Repeated wear in certain areas can begin to damage the fibers which make up your carpet. These areas begin to develop gray looking patches or track patterns which won’t come out even with a professional cleaning.