question #2 Sahih al-Bukhari 7361, Book 96, Hadith 88 : How can one assess the reliability of narrators when discussing historical or religious texts?

Narrated Humaid bin ‘Abdur-Rahman that he heard Mu’awiya talking to a group of people from Quraish at Al-Madina, and on mentioning Ka’b Al-Ashbar, he said, “He was one of the most truthful of those who used to talk about the people of the Scripture, yet we used to detect certain faults in his information.”