When it comes to verifying, it might there's a chance that you will know them more if you will join them on social media (there might be a presence on all social media platforms), do you might witness their progress and regular update through their social media platforms. And the most important is, the Whitepaper, there should be a realistic goal that makes their project more progressive in the future and of course don't forget the real use of their project, utility of the project must be important somehow.
While joining bounty programs you'll know the legitimacy of the project, there should no fraud activities, and must be transparent in all aspects.