Stigmatization among drug users and on online forums is inevitable. People will have their opinions, and so long as they're not hurting anyone, let them. Out in my neck of the woods, there isn't a whole lot of meth use (although I'm
way out of the 'scene' nowadays), but one drug I know causes a lot of stigmatization is crack / freebase cocaine. I've spoken to
hundreds of drug users over the years—junkies, tweakers, club kids, rich coke-and-booze snobs, pill poppers, beer-and-pot party kids, etc.—and the two drugs with the most controversy, stigma, and hatred surrounding them are methamphetamine and crack cocaine.
I've met plenty of die-hard I.V. heroin users who will clear out of
anywhere—probably even a free suite in the Ritz-Carlton—if even one tweaker shows up with a crack pipe. It's a weird thing, and it has roots in both reality and misconceptions. Of course, there are folks living on the street who've dealt with tweakers who've become violent, so I guess some of them are justified in being weary of crack and meth, but in general it doesn't make any sense why there's
so much stigma.
Concerning meth, a big part of its stigma comes from government-funded propaganda and sensationalist TV shows that were in heavy rotation during the late 90s and early 00s which portrayed it as this demonic drug that wrecked everything in its path, caused houses to blow up and/or catch fire, tore families apart, and all that. For many 'average' people, meth conjures up images of emaciated addicts covered in scabs with their teeth rotting out of their heads—essentially looking like zombies—so I think that's a big part of where the stigma comes from. That, and the crazy violent rampages that many tweakers have gone on.
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BTW, I'm new here. Hello everyone! 
I was a BlueLight-er
many moons ago when I was a teenager—probably active from like 2003-2006. I didn't log in for years, so per your rules, my account was deleted, which is fine. Anyways, I'm back, and
boy-oh-boy do I have plenty to share.