Most carpets are treated with stain resist properties and soil resistors known as Dupont Teflon or 3M Scothgard. After a period of 2 to 3 years, some of the soil-resistor wears off. At that point you should consider having a professional carpet cleaner re-apply the treatment after professional cleaning. The soil resistor will help the soil slide off of the carpet easier when vacuuming, spots will be easier to remove, and professional cleaning will be more effective.If you notice on the onsite protector demo below the fabric swatches on the left are both stained with a red dye. One has been treated with our fabric protector while the other has not. As you can see the one with protector repels the dye and the other is permanently stained.