Stain-resistant carpets are made of wool, nylon, polyester or olefin. Unlike other types of carpets, wool carpets usually aren't treated with special stain-preventing chemicals. However, they are resistant to both water- and oil-based stains, while other carpet materials are resistant to only one type of stain. The drawback of wool carpets is their cost.
Nylon is the most common carpet material. Its stain resistance depends on the quality of chemicals with which the fibers are treated. One nylon carpet can be very stain-resistant, while another can absorb any substance, so buyers should pay extra attention to the carpet manufacturer when choosing a nylon carpet. Nylon is somewhat less resistant to oil-based stains than wool.
While polyester and olefin are different materials, they have similar stain-proof qualities. These materials are oil-based, so they are very water-resistant, but they also attract oil-based liquids. It is best to use a polyester or olefin carpet in a room where it won't have much contact with oily materials. Aside from food, the two main sources of oil-based stains in a home are shoes and skin, so polyester and olefin are good choices for a room where nobody walks in their shoes or lies on the floor. These materials are fairly cheap.