Firstly, I think you have to be at least Junior Member to take part in Bounties, so you lack a merit to do that. Secondly, I would not go as far as recommending you a precific bounty, but if you want to make sure that it's not a scam - try to take a look at their team and check out whether it's not fake. You should also try to find some information about their registration and location. If this stuff checks out, I don't think people will really be risking that much by scamming people. Keep in mind, though, that even a good team with a nice project concept might still fail to be successful, so the tokens you earned can still be worthless after these steps, but that's just how life is.