As a lifelong reader, I think I have a decent say in the debate over whether the Tintin comics are racist in their portrayals of people who aren't white Europeans. My answer? Yes. Duh. Absolutely. Of course. Let the apologists argue over whether it was on purpose or whether Georges Remi was an innocent product of his times; I prefer to cede the debate entirely by admitting what is plainly obvious: Tintin, as a comic, is racist through and through. One has only to look at the Congolese of Tintin in the Congo to see this. For further examples, I recommend the black crew members of Cigars of the Pharaoh, the Muslims of The Red Sea Sharks, the hired guns of Rastapopulous and his gang in Flight 714 and dozens more.
Tintin himself is vehemently anti-racist, and is often seen sticking up for downtrodden locals over the objections of imperial powers (see: Zorrino in Prisoners of the Sun, Chang in The Blue Lotus). The trouble is that said locals are always portrayed as incapable of protecting or defending themselves, and in need of Tintin's intervention for their own safety. You could make similar cases about the inefficencies of provincial governments around the world that Tintin travels to, the political instabilities in various regions (the Balkans, the Middle East, South America) that Tintin regularly soothes, and so forth, but that's not the point.