I think everyone has their own approach to choosing a bounty campaign, someone is relying on the bounty manager, and someone is studying the project, white paper from and before joining the project, and somebody does not fix it at all and just takes it amount of bounty. so, I think, the main thing is to develop your own individual approach
Personally, I do both. I choose bounty from trustable campaign manager.
Then, I will study all of their projects. It's important to avoid failed or scam project.