Oh c'mon, Tintin's hardly Biggles is he 
It's one album in particular which causes all the trouble:
Tintin in the Congo, which is indeed pretty ghastly. It was meeting Chinese schoolchildren while working on
The Blue Lotus which convinced Hergé to research his books. Up until then, he just used the clichés that were prevalent among right-wing Catholic Europeans of his day.
Tintin in America, for example, is as guilty as this as
Tintin in the Congo, but the prevailing clichés about Americans weren't as poisonous as those about Africans.