Depends on the traffic of the area, places like corridor in the office, elevator lobby, industrial building with high circulation of people, should obtain cleaning service once every month; once every 3 to 4 months for other areas; once every half or a year for household carpet.
Since the carpet fiber had been damaged and worn out by the suppression of chairs, it would not disappear after carpet cleaning. Yet, by putting office chair floor protectors on the wheels could help to prevent and minimize marks.
Please do not use wet cloth or water to clean the toner, which will lead to dissolution and absorption. The right move is to use a vacuum cleaner to suck out the powdery toner, and then keep patting the affected area to get the toner out and use the vacuum again, remember to repeat this steps several times. If there are some marks left, you should contact professional service for assistance.
First press the area hard with a piece of white cloth to absorb the blood, then use warm water to wipe the surface gently, finally use neutralize carpet detergent and a sponge to clear the stains; when the stains were gone, use another towel to dry it. However, if the stains were left on the surface for too long, this method might not be applicable.
Use a clean white towel to absorb the coffee immediately, then use a towel with warm water to wipe the surface and repeat this step several times, finally use stain remover on the area to clear the stains completely.
The fibers within carpet were torn after long-term uses, the effect would be more visible on area with high circulation. When the stains were removed from the carpet service, the damage of the carpet would become more noticeable.