Exact.Polyesters are usually a brighter color as well and you can see the "glitter" is what I call it on the fibers.
Nylon generally duller color and not much wear pattern
Lol when I was a noob, I didn't take any carpet cleaning course, I had some experience of cleaning carpets for my dad in my teenage years but didn't know much about carpet types or upholstery types. So here I have started cleaning carpets for my own business, first couple of homes which had nylon turns out very well but the next 4-5 households with ugly worn off cheap poly use to make me work hard, and I am like what the hell, use to question myself how come some carpets came out very easily but some won't and give me the hassles. I started to notice the type of carpet from experience and later on I have done my carpet type research and found out the answer and took my Shaw carpet cleaning course and that cleared up more things for me, taking a training course is must plus experience.