nobody know early altcoin project will be successfully or being an scam altcoin but you can minimize the risk with do some research regarding upcoming altcoin project but it will not ensure you will get decent answers however you can check the feedback from this forum to determine the particular coin will scam or not and i think many people are willing to answers it
Detecting early will become possible only if a crypto currency is coming from a known team of scammers. Other than that there would be no significant methods to find out which coin will be successful and which one may go scam. That is the reason many people are afraid to invest with new projects.
But, when a new project is coming up with strong concepts and backed with a good team then we can freely go for investing with them. Still, anything may change over the course of time so we need to invest only what we can afford on the event of losing.
I do always ask for the opinion from my group of friends. Only based on their suggestion I do choose ICOs. So far, they are all good with their predictions which helped me making some decent returns out of my investments.