It is really hard to detect scammed bounty campaign. After completing all the requirements to be able to get accepted in a bounty campaign, spending much time to participate in forums and not to mention carrying their banners, completing all the tasks and reports then all of a sudden you will just find out that you have been scammed already. luckily I am not the only one but to think all participants did the same efforts as well as you did. But it is really happening, lesson learned and could be just charge it to experience and move on. If we could only find out at early stage if we were in to scam or a legit bounty campaign. Who would really know anyway?
The truth is, it is very easy ti get scammed by participating in a scam bounty campaign but if bounty hunters take out their time to do extensive research before participating then life would have been very easy. Most bounty hunters just decide to for the reward of what they are expecting during the campaign or at the end of the campaign this is not right and it seems not to be helping the community anymore. For a comprehensive guide on how to accept such check this thread:
https://bitcointalk.org/index.php?topic=5031657.msg45856516#msg45856516