What irks me a bit here is, that some things got mixed up in your post.

First, what do you mean by 'token has no value'? How do you define it? If you mean by 'no value' that it - at this time - has no trading value, then you need to ask yourself whether it's supposed to be already tradable or if you just have to wait. Is the project itself dead? There are projects that have tokens that aren't tradable for months after the ICO ended. And that is on purpose.

Second, what were your criteria for joining the bounty? They should be basically the same as investing in the project. In a sense, you do invest in it - at least your time.

The tips you've gotten so far in regard to joining campaigns with reputable Bounty Managers are good, but they don't absolve you from [arconym=Do your own research]DYOR[/acronym]. Even if you pick a reputable Bounty Manager, so what? That might only give you an additional security that you'll get your tokens, if they have value later on, who knows. Not all Bounty Managers get paid in tokens, they also get BTC, ETH and/or USD.