I dont think you can make a statement like that, without considering the other 50%. You could also say 50% of all icos are great. If you know what you are doing it is easy to distinguish bad and good projects.
All you need to do is to research deeply about every project. I am using telegram groups, youtube reviews and other resources to determine if a project is worth investing.


Resources:

Spreadsheets

Titan Research: https://docs.google.com/spreadsheets/d/1Ja83ZCDDOgNXNYatD5w-2grA8IENuSwGjtSHWOG247E
Tom Chase: https://docs.google.com/spreadsheets/d/1fhcTARkcktbagokKCwu_tdVHBYWj_wFIh90qo0ek1vE/edit#gid=0


My favourite youtuber:

TGO Network - TheGobOne https://www.youtube.com/channel/UCcbaSggxm8mApW2RG7psLrw