it's hard to find a good bounty, most of them are scams even managers with positive trust are no guarantee, because the manager only manages the bounty and payments are made by the project team, even projects that are successful in sales sometimes don't pay bounty participants, so before joining the bounty carefully research and wait for good fortune.
Even a good research cant give you guarantee. Just remember the Envion campaign? They collected 100 millions dolars and didnt pay to bounty participants despite the long company and strong support from bounty comunity