My people (the Germans) have this reputation for being impolite. I tend to think this is because we have the tendecy to be brutally direct when we want to be honest. We like to be honest, in that sense anyway, regarding matters of work. This comes off as rude to members of the civilized world (say, the British or Japanese). (I am writing this after +6 years of experience living in foreign countries.)

Another observation: the heroism around doing ones work is strong in Germany, we have that in common with the Americans (in the West, don't ask certain Asians). Yes, certainly there are many French (for instance) fellows, who like theire work. But the Germans (and Americans) have that tendency to get "macho" about it.