well, i guess you're guessing correctly about yourself, but you're guessing wrong about me (partially)
Most of the people who were busted working there ultimately died of liver failure.
as a chemist this doesn't surprise me at all. at every step you'll see, typically, something like 10g of solvent per 1g of product. then there's some solvent being used for purification as well, how much of it depends on technique being used. i doubt that visit of osha is the top concern of cartel lab manager, so these poor sods are going to be soaked in solvents, or at least solvent vapours 24/7. it's the liver that deals with it all and if it can't do it effectively, most notably this happens with chlorinated solvents (cheap, convenient, low boiling: DCM) liver gets fucked and that's the end result. some routes involve such friendly chemicals like benzyl chloride, this won't help either
when i was talking about impurities i was mostly talking about residual iodine, alkyl iodides, some weird phosphorus(III) compounds, occasional aziridine and such. similar compounds were responsible for side effects of a drug most commonly known as krokodil. i forgor about (R)-meth, chemically speaking, both (S)- and (R)- isomers are meth, these just differ in pharmacology, the active being (S)- and (R)- just being decongestant. usual P2P process provides 1:1 mix of them, but separation could probably make the process rather expensive (and what do you do with (R)-meth?). i suspect that instead someone developed an asymmetric P2P process, or something else entirely, which means that big meth labs moved from first year organic chemistry lab level to bsc thesis level. that's a progress, i guess, probably to be accompanied by new and exciting cases of heavy metal poisonings in the future
i understand it's a cultural thing. in US, as i suspect you are american, meth is sold in bulk drug of the poors, and amphetamine is (illegally) sold as pills to stock gamblers^W^W^W traders and SV engineers, that is the rich. this is absolutely not a global situation and for example in my country the street stimulant of choice is amphetamine sold as a bulk powder and i can assure you it can be every bit just as destructive. and this is before you consider things like alpha-pvp that have paranoia as an intended feature and there are people that like this effect specifically. goes without saying that street stimulant users won't be usually very picky about what they will try that day. just in the case it's unclear: i'm not saying that meth is good or that evil psychiatrists poison kids with adhd with drugs, i'm saying that you're underestimating how dangerous amphetamine can be, in some contexts, in comparison to meth.
my source for that is my own degree in organic chemistry, former flatmate that worked in harms reduction organization, and not having my head firmly embedded in my ass. i won't disturb your smug undeserved sense of superiority anymore, have a nice day