To make 100% to avoid scam is impossible because even the good project can turn into scam if one of their team member do,but you can prevent it by doing some research of the project you want to invest,escrow for an ICO i think it is not posible.
Also not all the projects that fail are scams, you just need to look at the world of businesses to know that most of them fail even if the owners had all the desire to become successful, and the same applies to the ico market, there are many good persons out there that are trying to develop something new but they are underestimating the difficulty and the costs that it will take and so the project will eventually fail.
Successful projects/owners dont really easily achieve that state because it would really need to convince the community to have that kind of support.Achieving success wont really happen just overtime but it would really need lots of factors to be seen until it would able to get such support. You are right that there are serious project owners that do really strive to succeed but difficulties would be faced wont really be that easy.