Honestly it is hard to identify the scam projects because all we know that scammers are not an idiot. But for me scam project are having a very good offer but while the project is on going suddenly all of features and procedure while change. And a good project will be recognized by it's existence and number of participant that will have and continues growth.
That's right, scammers are always smart at managing their projects, and when their projects are already a lot of interested, the rules are changed so that the project participants become their victims.