Crypto world is in crysis now and it's not only due to red market but also because of tons of scam ICOs. And that pisses a lot of bounty hunters off cause scam ICOs produce useless unworthy tokens! People waste sometimes several months to participatein bounty and either get no tokens or get shitcoins.
I've experienced like that before, I was participated to a ICO bounty by joining their facebook campaign then suddenly the ico's project had stopped without a statement from the team.
Well, that might looks like a waste since I spent for months by doing promote their project.

But how do you guys know if your bounty is trustable? Why do you personally trust bounty you're participating in right now?
Regarding to your question, I trust my bounty in several factors from my little research that include: the team is real(i mean showing up their face), their background, bounty manager, reading the whitepaper also the roadmap, and surely their project.