[alasdair_]

>Wouldn't even the shadiest of dealers want to keep their customers/hosts/victims around to, you know, keep bleeding money?

Not really, no.

For example: spike heroin with fentanyl, user dies, other users flock to that dealer who supposedly has extremely high quality heroin.

This tactic doesn't work as much now that the fentanyl epidemic is widespread and known but it certainly happened in the past.

Also, many dealers are addicts themselves. If they run out of money and need more drugs, what's the chances they will sell some bullshit and claim it's something else? What if they get into some other kind of trouble and need fast cash?