The reclusive and uncompromising Mrs. Costello represents the snobbish voice of high society, and the fact that Winterbourne takes her opinions to heart casts him in an unflattering light. Mrs. Costello is a shallow, self-important woman whose own children seem to have as little to do with her as possible, though Winterbourne seems quite willing to spend much of his time with her. He takes seriously her assessment of Daisy and her family and defends Daisy only feebly, characterizing her as “completely uncultivated” but “wonderfully pretty.” He tries to prove what a “nice” girl he thinks Daisy is by telling Mrs. Costello he plans to take her to the castle at Chillon, but Mrs. Costello finds the fact that Daisy agreed to the trip so soon after meeting him very troubling. She raises the question of whether Daisy is actually as nice as Winterbourne thinks she is. At the heart of Mrs. Costello’s suspicion is the extremely European idea that Daisy might be an adventuress—a sort of social hustler whose whole object is to trick Winterbourne into compromising her and therefore obligating him to marry her. Such women actually existed, and indeed, Winterbourne has encountered them in Europe before. However, Winterbourne suspects Daisy of this maneuver almost too easily, which calls his judgment into question.
Mrs. Costello objects to the Millers and mocks their pretensions for two reasons: first, since Mr. Miller made his money rather than inheriting it, the Millers represent “new money,” and second, they are vulgar. The Millers are vulgar, especially Daisy. She tells Winterbourne about having grilled the hotel chambermaid about his aunt, which is a vulgar thing to do, let alone to admit to Winterbourne. Daisy’s speech habits are a clue that James intends us to regard her critically. She talks endlessly and monotonously about herself, with frequent recourse to expressions such as the phrase “ever so” that undereducated Americans thought were “refined.” Daisy seems to regard every thought that runs through her mind worth expressing, which is an extraordinary kind of egotism. Daisy is also silly and vapid, and even the atmosphere of the castle at Chillon, with its historic and literary associations, fails to distract Daisy from the business of flirting. Her focus remains trained on the trivial and personal, her own and Winterbourne’s “tastes, habits, and intentions.” Daisy’s almost infantile approach to conversation seems to be a symptom of her larger inability to adapt to her surroundings.