This is EXACTLY why addicts often don't get the help they need. People buy into the myth that "meth not even once" will rot your teeth out and tear holes in your brain. Those are only the extreme cases, and it's often because the addicts already had mental issues and used drugs to cope as a side effect of their mental state not the drugs themselves.

Heroin in its pure form doesn't do damage to the skin (unless IV'd) or body (and no it doesn't kill brain cells). The damage comes from the peripheral effects of being an extreme addict like homelessness, poverty, no money for food (thin as a rail), no money for personal hygiene (tooth rot after many years of not brushing teeth or going to the dentists). It's super easy for rational drug users to hide being strung out on heroin or meth (way easy to hide it on meth), the only time you'll see people nodding the fuck out or twitching compulsively is from long binges and excessive use. And it's especially easy for rich people to hide it because they have the money to stay out of withdrawals which is where the actual negative effects of the drugs come out. Addicts with money can afford to buy cleaner uncut drugs, new unused needles, and stay the fuck away from the streets.

Sorry for the rant but this hits home as I've had 2 friends in my hometown overdose on heroin, one of them I just thought was a pothead but overall looked healthy and was band teacher. The other one was a super clean cut kid, very attractive, mid 20s and was about to graduate from a decent university and I only later found out that he was suffering from schizophrenia. I was around them all the fucking time but because they were pretty intelligent people and didn't look like the cartoon caricatures of extreme drug addicts no one knew or noticed any warning signs.