Of course you can not be 100% sure if something is a scam or not. But there are many good sources all over the internet where you can inform yourself
about a project as much as possible. I am not a big fan of crypto youtubers but there are some really good guys who take very deep looks into many ico's.
You can watch some of the videos to get some insights and then do your own research and decide for yourself which ico maybe worth investing. I think that is a good way especially for people
who are new to the crypto space. But please do not follow them blindly. Always do your own research.