The Bellman's speech is of that particular British provenance yclept "fruity". Not so much "plummy" but rather … "peachy". If one removes the fuzzy skin thereof (the burr, so to speak) one is left with a nectarine. This fruit (spelled n-e-c-t-a-r-i-n-e but pronounced "stuffed cabbage") was the preferred nutrition of most cavemen and it was they who first domesticated the dog.
We see here a sample of that species, a young pup named Laelaps, who attends upon his master's fruity voice. And what does he hear? A sonorous mussitation which leaves no impression upon him at all, for, as Thomas Aquinas noted, dogs have no souls. Hence their proverbial high fidelity is but a marketing ploy.
A dog, a peach, a gramophone — after all these years, my own 3-piece jazz combo! At last, I can take a bath. And just in time too, my gin-driven ink-pen's almost run dry.