Compare the dramatic value to the tea-table scene between Cecily and Gwendolen and the opening sequence of act III
During this very interesting scene in The Importance of Being Earnest, Gwendolyn and Cecily basically have a very polite showdown in which they sarcastically try to take control and hurt each other's egos in two very interestingly different ways.
The central element is tea. As a very important part of social sharing, tea, cake, and bread and butter were the objects that they used to have their intellectual catfight.
Since moments before Cecily had offended Gwendolyn politely when she nicely pointed out to Gwen how bad London society is, this was Gwen's turn to get back at Cecily.
The dramatic value is based on the actions not matching the words, the anger of each character's catty ways feeding on each other, reaching a climactic argument, and then finally solving it with the entrance of Jack in the scene.
In terms of the dialogue, when the tea service came Gwendolyn would refuse the options Cecily offered. When she offered whether she wanted cake or bread and butter, Gwen said that cake hasn't been " seen in London society proper homes for quite some time", and that sugar was "unfashionable". For this reason, Cecily gave her both cake AND sugar to the unsuspecting Gwen, and that was the final showdown.
Another good piece of dramatic value was each character's unwillingness to shy down to the other- Cecily could have easily felt threatened by the uber aristocratic Gwen, and Gwen could have felt beat down by the very proud country girl Cecily..but none did..and in the end we realize that they are both mirrors of each other, just in a different setting.