Comment by trhway

yes, while the show probably popularized the idea of purity for meth, in general strict prohibition leads to increase in purity and potency. We've recently seen that with heroin/fentanyl. There is probably still no "fentanyl of meth", and thus so far only purity increase. Once a more potent, fentanyl-like, meth appears, it will probably similarly get into and displace a lot of classic meth trade.