Or are we just arguing whether knowingly promoting a proven scam is untrustworthy behavior?
This is a more more interesting discussion. I'd say it says a lot about someone if they're willing to promote a known scam.
If you receive monetary compensation for this and are still willing, then this makes you an accomplice, i.e. a scammer per definition too. Regardless of which view you take on it, this should remain true in every.