It is very easy to spot scam bounty/project. But the real problem is how to spot a successful bounty before joining! Because you can join legit bounty/project and after months of work the project can simply announce the fail of the ICO and you will come empty handed after months of work. The time to spot scam projects only is gone and now is the time to spot the project that has a higher probability in raising money, and trust me it is not always about the quality of the project, so the best thing to do is to try to split your effort among some bounties not only one.