The fastest solution is to completely remove signatures and prevent people from making any profit by using this forum.
- prices could be: "ambassadors badges" , merit points etc. (at a certain number of validated/confirmed scams by admins you can receive different badges: bronze, silver, gold ...)
This way you will make things more complicated. You gave these people an opportunity to earn some money by creating more scam projects with the intention of reporting them and earning some money.
The higher the awareness, the higher the risk and the less scam.