There are some clues by which you can mark that is it scam or not? Very beginning of joining bounty campaign you should follow the manager. It is the very easy way that you can identify it is good or bad.
Ugghh, you just stated a vague step. If it is easy, can you state the sign that the bounty that bounty manager managing is a scam? So tell us, what should we look or a sign of the manager to tell that the campaign that he is managing is a scam.
Well, it is quite hard to tell if the project is a scam or not and we need to take extra steps in identifying one. One of the best method is to validate the project developers. Are they real people, do they use their real names or they just use a random picture and put a random name on them. Next is to validate their personal achievement. That way we can see it ourselves that these developers are really capable of bringing the project into realization.