In the early 18th century, the standard of Italian opera performances had become somewhat questionable. In 1720, The satirical writer Marcello offered some advice to those involved in opera performance:
[The opera performer] will hurry or slow down the pace of an aria, according to the caprice of the singers, and will conceal the displeasure which their insolence causes him by the reflection that his reputation, his solvency, and all his interest are in their hands.
…The director will see that all the best sings go to the prima donna, and if it becomes necessary to shorten the opera he will never allow her arias to be cut, but rather entire other scenes. [If a singer] has a scene with another actor, whom he is supposed to address when singing an air, he will take care to pay no attention to him, but will bow to the spectators in the loges, smile at the orchestra and the other players, in order that the audience may clearly understand that he is the Signor Forconi, Musico, and not the Prince Zoroaster, whom he is representing…
All the while the ritornello [the purely instrumental portion] of his air is being played the singer should walk about the stage, take snuff, complain to his friends that he is in bad voice, that he has a cold, etc., and while singing his aria he shall take care to remember that at the cadence he may pause as long as he pleases, and make runs, decorations, and ornaments according to his fancy; during which time the leader of the orchestra shall leave his place at the harpsichord, take a pinch of snuff, and wait until it shall please the singer to finish.
Furthermore, both serious and comic operas were essentially parades of arias. Between the arias, people would play chess. A visitor to Rome noted that “chess serves to fill out the boredom of the recitatives and the music serves to check too great a passion for chess.” (1)
Both quotes cited in: Marek, George (1969) Beethoven: Biography of a Genius. London: William Kimber, p.15.