• The claim "Sadiq Khan is grossly incompetent" is a subjective value judgment, not a verifiable factual statement.
• Competence in political office is assessed through opinion, policy debate, and electoral outcomes, not objective facts that can be fact-checked.
• No verified claim database entries match this statement, and there are no accepted quantitative metrics for "gross incompetence" that would allow a defensible validity percentage to be assigned.
• As a subjective opinion, the claim falls outside the scope of factual verification.

Overall validity: Unknown