Although admired by his contemporaries, he was also criticized for using his highly efficient secret police to spy not only on criminals but also on ordinary citizens. His services opened private letters sent through the mail, which was a frequent practice in Europe at the time, and spied on families. Sartine was thus aware of all sorts of scandals in the city, notably sexual scandals, and he sent daily reports to the king containing saucy and intimate details about courtiers, clerics, and private citizens, which were said to amuse the king and relieve him from the boredom of court life. Furthermore, his political police was known for its efficiency in detecting agitators, dissenters, anticlerical propagandists, and other people perceived as trouble makers, who were imprisoned without trial through the "lettres de cachet". Some sources say that there were never more political prisoners at the Bastille and at the fortress of Vincennes than under his tenure.