Why is it that the foreign pundits speak better than the English ones? Ian Wright should ashamed! How did he go through 12 years of school and not be told that it is think not fink?I would have got a bash round the head!
It could well have something to do with the fact that we are taught mainly by our parents, using their idiosyncracies and dialect. Foreigners are taught to speak English the correct way without dialect.
I find that today lots of folk (especially youngsters) use the f sound for th. I don't think that either mocking them, or bashing them round the head, would be particularly constructive.