3. What does Marguerite see her husband has a good head for when she enters the private rooms?

Marguerite notes that her husband is immensely organized and has a good sense for business.

Since she had entered this neat, orderly room, she had been taken so much by surprise, that this obvious proof of her husband's strong business capacities did not cause her more than a passing thought of wonder. But it also strengthened her in the now certain knowledge that, with his worldly inanities, his foppish ways, and foolish talk, he was not only wearing a mask, but was playing a deliberate and studied part.