There are so many bounty campaign that moderate by newbie with 2/3 activities, is that kind of bounty are safe and believable?
I think bounty campaign that moderate by newbie with 2/3 activities mostly are not safe and believable. Because creating a newbie id, wearing copper member title is very easy. So they don't worry about their id and they promote any bounty campaign without any research. On the other hand, high rank campaign managers, spend some of their time researching when promoting bounty.
If there's a chance to work with bounty managers with a higher rank and good trust score then you must choose it. I'm not saying working with newbie bounty manager is not safe as I believe there are also newbie bounty managers who had already run a successful bounty campaign, but think this way, a high rank with good trust rating is risking his account and therefore he will loss his account if he scam the bounty hunters.