First of all let's separate SCAMs and unsuccessful ICOs.
I agree with the majority of the comments in this thread that you first need to check white paper and team members.
1. In 99% of SCAM projects don't have real/valuable idea or business use case, which really need a blockchain to solve something.
2. As a rule, there are no people in the team with serious experience in the relevant field. That is, you need to check the command profile in the social networks like Linkedin, Facebook, etc. And pay attention when profiles were created.