You have analyse everything of an ICO, starting with the team, project, token metrics, previous works of the team, their Linkedin, twitter etc. Try to contact them and see if they are legit. But it's a long researching process to understand whether the ICO is scam or not. However if the team is famous and strong then I don't think you will have a problem of being scammed.
Definition TYPE OF SCAM for ico founder needs to be more explained. Maybe with the FAMOUS AND STRONG TEAM OR A BIG COMPANY will never take your money without given token and submit the token to an exchanger, But FAMOUS AND STRONG TEAM OR A BIG COMPANY always take a people money and give shit token without future then they start another ICO do again and again.
https://bitcointalk.org/index.php?topic=5045723.msg46630825#msg46630825