There is nothing anyone can know with 100% certainty, no matter what the source is.
Life is all a series of choices based on probabilities and risk assessments. There is no trust, only the best information at the time. Trust is a label you assign to something AFTER you made the probability calculation in your subconscious mind. Never before.
The best way to get more accurate at probability calculations and risk assessments is for a person to actually take risks. Otherwise, your life will be riddled with choices based on poor risk calculations by default. like a newborn. Even if you try to learn from the mistakes of others, you won't understand the mechanisms of the consequence if you have not actually experienced a parallel situation.
Imagine you saw a person die in a car crash. If you have never seen a car or driven a car before, you might assume getting into a car will kill you. It would demonstrate poor risk assessment. Only by taking the personal risk of riding in a car or driving a car can you understand the mechanisms that are involved in calculating the actual risk of death due to being in a moving car.
This recent COVID 19 event demonstrates how diverse the public is on personal risk assessment accuracy. Some of the pop videos are downright comical.