Suponho que você esteja se referindo a este trecho do livro
‘So ends the famous Harry Potter,’ said Riddle’s distant voice. ‘Alone in the Chamber of Secrets, forsaken by his friends, defeated at last by the Dark Lord he so unwisely challenged. You’ll be back with your dear Mudblood mother soon, Harry … She bought you twelve years of borrowed time … but Lord Voldemort got you in the end, as you knew he must.’
Sob as circunstâncias, acho que podemos supor que ele estava usando um tom zombeteiro e praticamente cuspiu a palavra "sangue-ruim" dada a sua conhecido animosidade para quem não é puro sangue.
Em Half Blood Prince, Voldemort fala novamente sobre seus sentimentos sobre os sangue-ruins, desta vez com "raiva e desprezo":
...last week Professor Burbage wrote an impassioned defence of Mudbloods in the Daily Prophet. Wizards, she says, must accept these thieves of their knowledge and magic. The dwindling of the pure-bloods is, says Professor Burbage, a most desirable circumstance … she would have us all mate with Muggles … or, no doubt, werewolves …’ Nobody laughed this time: there was no mistaking the anger and contempt in Voldemort’s voice.
E em Relíquias da Morte, ele faz praticamente o mesmo discurso que fez em Câmara Secreta, desta vez em um falso tom de autocongratulação descrito como " zombando "
‘Is it love again?’ said Voldemort, his snake’s face jeering, ‘Dumbledore’s favourite solution, love, which he claimed conquered death, though love did not stop him falling from the Tower and breaking like an old waxwork? Love, which did not prevent me stamping out your Mudblood mother like a cockroach, Potter – and nobody seems to love you enough to run forwards this time, and take my curse. So what will stop you dying now when I strike?’
Eu acho que é justo dizer que, embora o tom de Voldemort seja geralmente descrito como bastante equilibrado, sempre que surge a questão da pureza do sangue, é algo que engendra grande paixão nele.