[A. Pole]

In Mother Theresa's case, we could be confident that she was telling the truth, even if we happened to disagree with her.

Reread your own sentence - it is absurd.

Of course if one is not capable to evaluate what is being said or written one is doomed to to rely on personal trust.

Machiavelli stated:

"Three minds exist; one capable of thinking for itself; another able to understand others' thinking's; and a third that can do neither. The first mind is of the highest excellence, the second excellent, and the third worthless."

[AnAmericanMother]

No, you continue to analyze, but when you have experience of a person as honorable and truthful, you can employ a different level of analysis.

In other words, you consider what they say to be truthful and accurate within the scope of their knowledge. You can trust that they are not deliberately lying, manufacturing information, or seeking to mislead.

When a person is a known "spinner" (a polite word for "liar"), then a far more suspicious attitude has to be taken to any assertion he makes. Colloquially, "if he said the sun rose in the east, I would go outside and check."