It's not too easy to spot scam projects but one can always carry out an extensive research to ascertain which project is legit and which is fake. Although sometimes it's almost impossible but there's always a flaw somewhere forgotten by the team. It's quiet painful to work for 3 or 4 months without being paid.
if we analize project in detail , i think we will found the flaw of their projects.maybe in their whitepaper , team picture, reddit, github , or even in their smartcontract.always check it one by one to found it.