Little is to be gained by kicking skunks or entering into a spitting contest with camels.
Few falsehoods deserve response.
The adversary will often use such things to divert our attention from the greater labor of declaring our message. President Ezra Taft Benson shared an experience he had as a young missionary in the British Isles that illustrates the principle. He and his companion were invited to speak in the South Shields Branch. Elder Benson was assigned to speak on the Apostasy and prepared himself to do so. When he stood to speak, he felt a strong impression to talk about the Book of Mormon, which he did.