Wharton's prose is as proper and intricately gilded as the furniture in the Trenors' drawing room. In the Victorian era, everything from cleavage to ankles to furniture legs were hidden, and, similarly, the much of the action in House of Mirth (revenge, sex, seduction, lust) is hidden in sub-text. When Trenor propositions Lily, all he actually says is, "The man who pays for dinner is generally allowed a seat at the table."
Wharton also has a knack for saying a lot with a little. Try to re-word some of her more incisive one-liners and you'll find yourself buried in a paragraph of dull text. For example:
If [Judy] was careless of [her husband's] affections, she was plainly jealous of his pocket. (2.4.43)
Basically, this is really good writing.