We can not be sure that where the bounty nice and proved to pay, many predict if the bounty is good and eventually, the price of the market her is not good and there is a bounty that underestimated instead give a surprise, so do not too much thought, joined the first and feel the result in the end.
Are you worry about the bounty campaigns paying for your work? If I am right choose the best project managed by the trusted managers like Yahoo, Ahmad, Jamal aezez or Atriz. They were perfect in the payment. I see yahoo especially takes the time to get the payment for participants until paid.
If you find the project comes with the unknown manager and fake profiles on their project's social media links. Please ignore those kind of project first. You will be a looser then.