that s the million dollar question of the moment... ICO s are trustable of not? In my personal experience i had some successful ICO s and shit ones as well, but never got scammed. at least until now..
also i didn t participate in a lot of them, arround 3/4 per year...
First, Escrow in ICO is the "safety net" of it. Without it don t bother. Also you should read a lot about the project, investigate about it, gather knowledge where your money is going at. Trust able Devs and with previous knowned projects is half way to the sucess.
To avoid all the risk and to minimize lost, don t invest Btc on ICOs, instead invest time. Join bounties. They are also a nice way of avoiding scam ICO s.