How can we identify when a scammer is trying to scam.
I believe it is simple, their offer is too good to be true. If we keep our greed at bay, we can easily see their scammy plot because almost all their offer are those that will trigger our greed and make our brain think irrational. Aside from that, we also need to educate ourselves and do research in every offer of investment we meet. Patience and thorough research will always save us from the claws of these scam people.
If something is far from the reality or if the project is too good to be true, then there should be curiousity. Curiousity must be followed by action of checking if it is true or not. There are many ways to do so; asking other people inside and outside the project or checking for its background. Think of it as "there's no way a project will be this much". And if you won't lose that much from engaging if there's no other way, go for it. Sometimes risking is worthy of one's time.