What is the sound approach to a historical critic’s use of «kadhaba»?

Reports of ʿAmr ibn ʿUbayd: Attribution, Conflicting Accounts and Evidence of Criticism

• Classifying all of a narrator’s routes as fabricated from one label alone
• Ignoring all other particular evidence on finding one contradiction
• Examine speaker, instance and supporting context
• Reducing «kadhaba» invariably to unintentional error