Invest in ICOs that have products already. That is a single indication that it might not be a scam. Projects with products already simply means they are already functioning even without the ICO, perhaps the ICO is needed for the improvement or advancement or extension of the project. Those that have no products might be relying too much on the ICO and when the ICO gathers too small or fails, there is probability that the project will fail as well because they did gather the necessary resources.