Opera or operetta?

Tell me if this criterion works. When the music is good and the audience finds it good fun, it's an opera. When the music is dreadful and the audience is dreadfully affected, it's an operetta.

Yes, I understand the metric is unconventional and that it fails to distinguish between Wagner and Strauss, but perhaps inducing the S1 circle topology (as opposed to the R1 real topology) is actually a strength.