Good advice is always certain to be ignored, but that's no reason not to give it.

This aphorism is very widely credited to Agatha Christie and circulates in a strikingly stable form — "Good advice is always certain to be ignored, but that's no reason not to give it" — across quote collections and anthologies of her sayings. Yet despite that consensus, we could not tie it to a specific source: it does not appear with a citation to any of her novels, her autobiography, her published correspondence, or any reprinted speech, and targeted searches of her minor and out-of-print works turned up nothing. The line is wry and consistent with Christie's voice, and we found no rival claimant or earlier user to unseat her, so we have no reason to doubt the attribution outright. But without a traceable original — every appearance rests on aggregator repetition rather than a primary text — we classify it as attributed rather than verified. If a Christie novel, letter, or interview bearing these exact words comes to light, this can be upgraded accordingly.