How does Farr (1991) justify Tintin's appeal to adults?

Farr (1991) justifies Tin Tin's appeal to adults not just for the comedic aspects, but for the political satire, the parody, puns and foreknowledge in which the comics establish. Farr says 'read the stories any number of times and still discover something new; they bear repeated re-reading'. Tin Tin began as a weekly Thursday illustration for children then gained universal appeal. It was in Herge's ability to stretch Tin Tin from a birthplace in Brussels, to the four corners of the world, with stories anchored firmly in fact with topics relevant to the current events of the stories. Not to mention the compelling narrative and well illustrated stories. Tin Tin offers many levels of adventures which can be appreciated by all from childhood, to adulthood to parenthood. 'The adventures, like their hero, are inexhaustible' (Farr, 1991)