A soiled baby with a neglected nose cannot be conscientiously regarded as a thing of beauty.

In this wry, deliberately unromantic observation, Twain punctures the sentimental habit of calling every infant “beautiful” regardless of obvious reality. By specifying a “soiled baby” and a “neglected nose,” he grounds the idea of beauty in cleanliness and care rather than in automatic affection or social convention. The adverb “conscientiously” is key: he frames honesty about appearances as a matter of moral integrity, not mere rudeness. The line fits Twain’s broader satirical impulse to expose cant—polite, inherited phrases people repeat without thinking—and to insist that clear-eyed description is preferable to comforting cliché.