Solution: It's very hard to find solution. But I think it's not impossible. First try to find multiple account holder and report to managers. So that many participant will be disqualify. Before participate any bounty do your best research what can you do. And share your opinion with others by reply on thread or ANN.
Managers should minimum research about ICO before start. If they exit scam that's is different case. But before start should little bit research what you feel. Don't be selfish. And you can limited participant for bounty to get quality promotion.
For participant try to choose best and reputed managers in order to get good payment. Avoid immature managers.
I just share my thought. If you have more idea it will be much appriceated to share here.
It isn't easy to find multiple account. Just because of mistakes from them, so we can find out multiple account. If no mistakes like same wallet address, same twitter/facebook, you can not find out. Forum doesn't restrict same IP for multiple account.
5) Unlimited participant: There is no limited participant most of bounty( not all) . If 10K participant then stake will distribute according to amount on participant and token are allocated. Simply you will get less token.
I think its main point of low payment in bounty. Because of unlimited participants, more people are coming everyday, that's why I give up on a bounty campaign that have 1K5 - 2K participants. Its waste time when you done 2 - 3 months of bounty, and receive only few tokens. We are bounty hunters, want limited participants to get more tokens, but project want more people to come, so they don't limit number of participants