it is really hard, what I check are:
1- is the bounty manager using that signature?
2- what is the total budget for the signature campaign? ***How much is the total budget **** What is the hard cap?
If the hard cap of the project is 300M dollars, that's silly. Because hard caps under 10-50M dollars are legit. No way the project can directly have 300M, even great projects don't have 300M market cap right now. Be realistic.
If the hard cap is 30M and the campaign budget is more than 400K usd, that is a nice campaign for me
3- check some legit reviews about the ICO, not paid advertisements