I think, much like Chinese manufacturing in general, the quality of “bulk poly strings” has increased greatly in the last 10 years.
That said, you’re right – most name brand bulk poly isn’t bad at all… these days. There is quite a bit of variance in feel though, blueprint for example was quite “rough” and had a very interesting feel, but isn’t around any more.
I’ve had the most erratic “love it or hate it” results with fancier super-boutique strings and especially nylons.