Generally we've had a policy of not teleporting negative trust, as this is trust gained on another forum and not necessarily reflective of their reputation on this forum. Positive feedback is different, and can be done as is beneficial to bounty managers and users alike.
That said there is a reputation section for a reason. If scam accusations are accurately presented, and there is support from respectable members of the forum to label the user as a scammer, then I'd apply the badge myself, nevermind the negative trust. Ideally we can think beyond a "he said she said" type trust system and simply apply a scammer tag where necessary, given that elected Judges already have the jurisdiction to do that, ie VP can crack on if wishing to engage in such activity.
Users just need to step up and create the necessary topics here if they want users punished, not expecting admin or global mods to do the heavy lifting as it were

This is the badge I mean, rather than having just -X feedback.
