It's not that you can't avoid it; however, you should first know that not every failing project is already a scam and can be labeled as such. I mean, you should try to look at it from the developers' standpoint, as much as they want to settle their dues and accounts, and pay the people who have invested in their project, what can they use if they also have nothing earned from the project, right? I mean, if you really want to avoid scam ICOs, the real ones perhaps, you should be meticulous in studying them, their background, the people behind it, and most importantly, their objects that would give you the general idea how the project will continue in the future. At least, if you have studied it well before committing to it, even if it would turn out to be a bad one, you won't have that much regrets since you did your part.