There are many factors and of course between ICO with each other is different. There is no definite benchmark. It could be an ICO has a good concept and a good team but in progress it turns out it is a scam. If you have experience in ICO certainly the ability to analyze is increasing. At least you can see an earlier ICO project with the same team whether successful or not.
Unfortunately, very rarely the same team having the experience of successful ICO launches new projects. If this happens, then all investments are made by large funds and there is no room for investing ordinary people.