I will say it depends on project to project and one need to do his/her own due deligence. You should always look for what real life problem the project is solving or is it doing any value addition. Just a coin/token with no business velue is useless. Everyone claims they are better than Bitcoin now days. Ether on the other side allows anyone to create a token in 5 minutes .
So join their Social media channels, ask as many questions you want. if they avoid to answer, they are not legit.
You won't get any better answer then this one. Mainly you need to do your own research, once you believe in such project then it's time to work with them by any bounty that you are willing to fulfill.
