For some, yes. One has to have the cognitive ability to separate the messenger from the content.
The messenger is part of the content. If Alex Jones screams some anti-liberal hate, I can rationally make some assumptions about the quality of his message before even committing time and energy to vetting his statements. This is normal, and vetting all statements would be impossible. This is a useful filter, if applied prudently.
The messenger does not automatically discredit the message. Even a broken clock is right twice a day.
For many people, yes. None of the critics here, for example, has challenged a single element of the article as factually false (let alone providing any supporting data for same).