Ḍabṭ is not established merely by praising a narrator. Specialists compare his reports with those preserved by established transmitters, distinguishing general agreement, isolated mistakes, and a recurrent pattern of serious contradiction.
Suppose a transmitter generally agrees across several well-attested routes but differs in one expression; that alone does not establish habitual unreliability. Persistent, material contradictions prompt a different assessment. The nature of each divergence and its supporting evidence still matter.