You have to choose the bounty that has a good and reliable manager. If you are feeling depressed that your efforts were wasted that's the other side of bounties.
If they aren't able to reach their soft/hard cap they will never pay your efforts so if you want to get paid with the bounty you are joining. Just choose the bounty that has an experienced bounty manager and assures the participants to get paid.
Yes, you are right mate. It's better to search and choosed the bounty manager who have a lot of experienced in managing the campaigns and have trusted and gain positive feedbacks from the people. By this, the chance to be paid or get bounty rewards will be possible to achieved.