You are right. There are lot of scam ICOs. So you should learn how to analyze ICO before investing. In any ICO you should check the project first. What are they want to do, if it has any potential. Also see their private sale and pre sale progress. How successful they are in those events. Read their whitepapers. Good ICO will deliver top notch presentation. Also investigate the members.
There are really risks in investing, even this icos that really have a great features suddenly turned scammed. Like everyone else is saying, only invest what we can afford to lose.
You are right with this, even the most popular ico can even turn scammed after their successful ico, this happened many times now and I have seen those icos already made their exit scammed. We just really need to invest good amount that we can accept if ever we loss it.