Nylon is the best carpet fiber on the market today. It is soft, resilient and durable. Grades of nylon in quality carpets are resistant to staining and it is easily cleaned. The best nylon is BCF or Bulk Continuous Filament. Non BCF carpet is made from staple yarn. Staple is made up of small strands of fiber spun together like wool is. When you vacuum a new carpet and get a lot of fuzz in your vacuum bag, its staple yarn. BCF nylon never sheds and looks newer and lasts longer. A fun fact: NYLON is comprised of the initials of the 2 cities where the DuPont teams developed the fiber, NY for New York, and LON for London.
Olefin fiber is made from polypropylene plastic. It is an oily fiber that has the tendency to attract oil to it. It soils faster than any other carpet fiber. It is one of the hardest carpet materials to clean. Another drawback to olefin is tendency to become dingy. When light colored olefin get dirty and you walk on the dirt (even with bare feet) you grind the dirt into fibers. After the carpet is cleaned the path that was dirty still looks dingy. This is because of the damage done to the fibers reflect light differently that the rest of the carpet. Olefin is more susceptible to becoming dingy because the stiffer fiber doesn’t move out of the way of dirt. Its stiffness makes it scratch easier.
All synthetic fibers can be scratched by soil. The best way to avoid this is to clean the carpet before it looks dirty. You may ask why in the world would I clean carpet when it's not dirty. Carpet can hold I lot of dirt before it is visible. Once you see dirt in carpet it is too late. You have already started to damage the fiber by walking on it. You should maintain your carpet as you would your car. You wouldn't wait to change your car's oil until you have engine problems, too late. My customers who regularly schedule cleaning of their carpet, keep their carpet looking new indefinitely. Carpet doesn't wear out, it uglies out!
I strongly advise customers to avoid polyester fiber, and I firmly believe it should never be used in carpet. It is the poorest performing and least expensive material used in carpet. Polyester cleans easier than olefin but not nearly as well as nylon. The problem with polyester is its appearance level drops fairly quickly, especially if it is a low-density style. It resiliency is very poor and it tends to matt in traffic areas, especially where traffic flow turns. Furniture legs leave permanent indents in the fibers. Areas under chairs like in dining rooms develop multiple indents that can grow to 6 to 8 inch matted areas. Matting on polyester is not correctable by vacuuming or cleaning. Polyester carpet often times has the appearance of 10 year-old carpeting after only 6 months. In my career as a certified carpet inspector, I’ve inspected many polyester installations. It is common in my experience that I would come across consumers that were very upset with their purchase because shortly after installation, the appearance level had dropped significantly due to the poor durability. Whenever you find a great price on carpet, check to make sure it is not polyester. There is a new polyester on the market. They keep trying to reinvent polyester because of it's bad reputation. This new material uses corn added the the polyester. It has several names. This new material has a feel very much like nylon. The only improvement is in it's feel. The drawback is in it's cleanability. It is advertised as the most cleanable carpet ever made, when in fact it is the least cleanable carpet. It will clean but with extreme effort. The cost to get this carpet clean could cost many time the price of other carpet.