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Extensive reseach is really a must and aside from checking their location, the team transparency is necessary to check if they are real people and not a picture of someone in google.
which is not an easy task if you are from another country or even from the other side of the world ...
Unfortunately, if you do not know the team personally or at least one of your trusted friends knows them (of course I mean "real" friend and not person who you know only via the network) there will be no certainty.
If a scammer plans to rob hundreds (or thousands) of people, he is able to devote raelly a lot of time and resources to make his scam look as credible as possible, what is investing a few thousand dollars in preparing a great-looking project if there is a chance for many times greater profit ...