To be honest Sir, there is no way for you to know if its a scam. In my opinion, some ICO's are legit but they are unable to sell the hard cap so it ended up being a scam. Trusted managers will not help if the ICO will not send tokens. What I have done is to keep on joining ICO's until I reach an ICO who will send me their token and wait for the alt to have its value on the trade.

I prefer trusted managers because they are organized and easy to talked with. Try Sylon, BlockEye, iwantpony, dafar and my signature right now momopi.