Yes, it is true, many bounty hunters do not research on project before joining the bounties. Before joining any bounties, we need to read the whitepaper, check roadmap of the company and check dev team, advisors as well as check the rating of the project so that we can avoid scam projects.
I myself don't pay much attention to that. the first thing I saw was the manager who published the campaign. and after that I will see more specific projects.
The choice of a bounty manager cannot be a major factor. a lot of successful campaigns were conducted by not very popular bounty managers