The bounty hunter must choose the most promising and paying campaigns, and if he isn't feeling comfortable with the bounty rules, the best decision is staying away from participating. We can't blame the bounty manager, because he is simply doing his work, so we need to check the quality of the project and the bounty's rules before joining.
It is very difficult to know those bounty that will reward you as some of them that look good and were well promoted on this forum, Facebook and Twitter has lose in the really market. Some of the bounty refused to share the stake and tokens to the bounty hunter because of the fear that if those tokens are share to the hunter, there are going to dump them in the exchange.
I see participating in baunty not much different from gambling! you only need luck to promote the only that will benefit you at the end.