Forum scams are not moderated, I know that. And I also understand that self-moderation can be used by conscientious users to prevent spam. But why do scammers have the opportunity to moderate their scam on their own?
In general we already have the answer here and maybe this is why there is no limit for scammmers to moderate their scam in forum. I think every user just needs to review one's trust rating before making a trade, it has been suggested thousands of times by forum users. If the admin or moderator restricts it with the system, it means that the forum is ready to moderate the fraud which they have not done so far.
I remember very well how 1xbit was allowed to run its campaign on the forum while the site proved to be deceiving many of its customers. So I think whatever the problem is when it is related to a scam then the forum will not moderate it. Yes, we can only suggest the best but the admin will decide everything.