Tintin taught me racism!
So, except for the Tintin in Congo book, what are you basing this on?
The way Herge wrote and drew was just the general mindset at the time, the 1930s. Yes, it was racist, but it wasn't out of place. Actually, the book was remarkedly light-racist compared to some view points at the time and place. (This is something that I'm pretty ashamed of about Belgium, but it's true that there was barely any resistance the German occupation once they were there - I recommend 'The Sorrow of Belgium' as a pretty good read).
From the third book onwards (I don't even remember any in the second book, except for where the native americans are driven of their land for oil?), there is barely any racism at all. One of Tintin's best friends is Chinese, Tintin travels all over the world exploring new cultures, bla bla bla. They're fun comics, but somehow, like people do, there is this immense focus on the negative aspects portrayed in the earlier work.
(Also, reading those strips in the Economist in English was just weird)