You are actually correct. Many of the "pipe cleaners" sold in craft stores are not cotton fiber and do not work as well as genuine pipe cleaners...
I think the ones I bought at walmart last time (in the crafts section) were made of polyester or some very plastic like "fiber". I tried using them to clean and they just sucked at the job. They're mostly meant for kids crafts.
Walgreens in my area still sells a 3pack of bristle pipe cleaners in the tobacco section behind the counter, so those work for me.