>>10291388 >>10291407 >>10291413
Polyester, in our modern era, has equal parts positive to negative just like Cotton. The issue is more cottons of varying quality and price point are still rather good, were Poly is specifically good or bed on very precise variants; so there is a higher change you could end up with a "bad" poly. As an example; polyester locks colors in better so the dye maintains a consistent appearance over most of the life cycle of the garment. By contrast, dyes applied to natural fabrics like Cotton will often look brighter and more vibrant at the beginning of the garment's life cycle, but will likely fade in saturation over time with washing. Again, the poly seems more "flat" to start, but it will consistently hold it's original color almost indefinitely. But then on the flip side you have the breath-ability factor; Cotton, Linen, Hemp and Wool will always breath far better then Poly.
Overall I think the main issue is not paying closer attention to material selection; with cotton you can "shoot from the hip" when picking your source and will -likely- end up with fine/okay cotton. With Poly you need to be really on top of being aware of what's available, what mills make the better versions and such.