In a different thread, someone posted a pic of a steel MTB with carbon fork. It had hit a tree. Fork looked perfect but both top tube and down tube were almost completely severed and bent about 30 degrees. Frame obviously destroyed but the fork looked ready to go onto another bike. Did it have hidden damage? Then there is the possibility of construction flaws. I used to build fiberglass boats. Work that is pretty can be fatally flawed. (And how much to the factories pay their help to get high quality laminates?)
As one who has paid big time for hidden damage in a fork, I will only ride forks that (almost always) show their damage. And even when I cannot see it, so far, those forks have always made it known something was wrong without me looking.
Ben