It is a lost cause, Customers are at the mercy of the carpet sales people and they swear by polyester carpet. Recently I purchased new carpet for my upstairs and the sales guy pushed polyester like it was the best thing since sliced bread. I told him i wanted nylon and he said Nylon is not stain resistant like polyester when i asked him about the crushing effect that polyester suffers from he knew nothing of it, then when i asked him about how oil and grease bond with polyester he knew nothing of that as well.
The reason they push polyester so hard is that polyester cost a lot less to make than nylon yet they sell it at a premium price. The salesmen get a bigger commision so they push the poly. I work for many apartment complexes and their carpet installers are pushing polyester hard. I had a face to face with the Sherman Williams rep and infront of the regional manager he stated that the polyester carpet will clean up like new with water over 140 degrees, I laughed and told him "I have a TM outside that produces 200 degree plus water, would you please give me a demo" He declined and tried to imply that any good carpet cleaner should love polyester because it makes their life so much easier.
This particular regional fell for the reps BS and behind my back hired stanley steamer to clean a bad polyester, they failed and now they have switched back to Nylon carpet.