One of the reasons why I still join in some bounties and believe in them is because I do believe in the manager campaign of the bounty.
Commonly, the bounty manager with their good track record and experience will serve the good bounty )although it is not the only one term to consider).
We can trust them to analyze their bounty program that will be managed.
Besides, to avoid such scams, we must be also careful and smart in choosing the right ICO for the bounty. Learn the project, token supply, allocation, and the softcap reach.
Of course, we cannot guarantee that the bounty is not the scam, but at least, we can try to avoid it.