I think it should be allowed to open a scammer flag against someone without personally being a victim if:

• Victims have actually been scammed/lost money
• The accusation contains enough factual evidence

Perhaps a rule could be added that a scam accusation needs to receive an x amount of merit before being able to add a scammer flag while not being a victim, showing that accusation has received enough support from the community.

EDIT:

An accusation like this: