I had a list somewhere with every drug taken, had over 20 something a few years ago. I was never afraid of any of them, took whatever, whenever possible. Was a opiate freak, got stuck on smack, got on methadone, then buprenorphine (subutex/subuxone), now trying my best to stay sober and failing.
The "final hit and then im clean" is an exellent way of doing it wrong. The withdrawle is unbearable with these synthetic opiates, waaay too long. With smack it´s just a week of heavy suffering and then you get better. Buprenorphine is a bitch, takes forever to get off. The worst part is actually staying sober after you quit, impossible. You almost envy (meth)amphetamine abusers. A funny thing about meth is that it is not all that. You will not loose your mind and chew off your elbows by just doing a line, its staying up for days and ignoring you hygene that makes you look like shit. Coke is a mild drug, all the pussies do it, crack just sucks. Ecstasy is fun, serothonine kick, love and every thing positive, a lush. So yes, a lot of people are missinformed.
The problem with opiates is that they blend in and sneak into you life so smoothly you´ll have a big problem admitting that you have one. That was my misstake, do not replicate at home.