I experienced to join bounty with so much waiting time. It takes months before they completely distribute the rewards. Some unpaid bounty efforts are scams. Scammers are clever enough to find ways in order to lure and trick other. This cause useless effort due to some bounties don't paid hunters who make so much effort in order to earn. There are lot of reasons why some of the bounties can't pay the hunters because of not reaching softcap, cancelation of projects and don't gain investors, making them no choice to fund the hunters effort.