There are a lot of scam bounties in the altcoin section but its your fault to participate into them without checking the project, manager and if they actually have the budget in order to pay the participants. I had been myself in similar scenarios and since them I'm never going to participate into bounties who aren't have the necessary reserved budget of coins for the hunters as most of them simply announce the pool for bounty but after it ends they say " Oh, we're sorry but we didn't gather the sufficient funds in order to pay the bounty hunters".

Also please check this thread to see the most trusted bounty hunters on Bitcointalk --> https://bitcointalk.org/index.php?topic=4412712