It completely depends on what is actually said, who is saying it, other extraneous, or specific facts that you have.
Are you aware of particular people lying to you? Have you been happy with the information that has been given to you? It just depends upon your relationship with the person in question.
I pretty much have no reason to doubt my best friend. She has no known agenda against me, and she’s a smart, well educated person, and she loves/likes/respects me.
Donald Trump does not know me, has been known to lie on a regular basis, and has little to no respect for women, minorities, and foreigners, and doesn’t agree with my basic tenets of decentness, so I pretty much assume that most of what he says is bullshit, lacks facts, ot has little basis in reality.