Heroin is a little bit different than cocaine. Cocaine is a much more social drug so you will see a larger number of non addict customers to addict customers.

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.