I think scammers in bounties should be given a negative trust or should be bound from joining bounties. This process will help reduce the rate of scam because most managers do not accept participant with negative trust in their campaign.
this is already done by DT members and moderators of this forum but since there is a huge number of users and multiple accounts you can't pin point every single one of them, but I highly appreciate the works of moderators although it seems that it's not easy to detect each scammers of bounty programs.
Sometimes it is impossible to find the bounty participant scammers but Moderators are doing their best to find the bounty scammers. Every person will do some mistakes on the basis mistakes i hope Moderators will find the multiple account holders.