'There should be no coughing in Act Four of La Traviata,' said Verdi, who knew a thing or two when it came to the stagings of his operas. It's a shame that neither the soprano (Inva Mula) nor the revival director (Daniel Dooner) heeded this advice on Saturday, for the entire last act was filled with such violent expectoration you could barely hear the orchestra. As you might imagine, this dramatic overkill almost toppled the death scene into comedy.