What was the reaction of the party guests when Nick asked where he could find their host?

Nick is repulsed by the shallow superficially of the people at the party. The people have no other interest other than money and the illusion of happiness rather than happiness itself. The Jazz Age, at least for filthy rich, is a world of consumption and flat characters.

Explanation:

This is true because generalities cannot prove anything.

Generalities are untruthful but they are often used so as to quickly convey a message. Even though we might understand what the person is trying to say, we must also understand that specific evidence of a situation always beats generalities.