The point is dealers will cut with unsavoury shit. They're not stupid enough to cut with poison but they are stupid enough to cut with shit that will turn people away.
Actually it's not unlikely.. South Dallas has a problem with stuff - cheap heroin cut with Tylenol PM. cheap and common. about $3 a hit.
Plus emphasis on sedative. Paracetamol has a synergistic effect with opiates. It wouldn't do the opposite of what it's meant to do. It's more like mixing caffeine tabs with heroin.
Heroin cut with Tylenol would be a non-issue to a heroin addict. Heroin is considered dirty to the many people who these dealers serviced (yeah I know). I doubt they served many of any cocaine addicts. Just people with nothing better to do on a Friday looking to have a "good time".
I know they no longer deal because one got run out of town after squandering about a thousand quids worth of the stuff on loan with nothing to show for it.