> a Swede who spoke fluent French (and German) who found one gas station
> attendent in France who would only speak to him in English (not very
> fluent English.)

I've found an interesting quandary, where the two parties in the
conversation would really like to practive the language of the other.
Years ago, we hosted a Japanese exchange student. I wasn't to study
Japanese formally until a couple of years later, but I had enough to be
dangerous. So out came my pile of dictionaries, grammars and other
guides, and I did my best. A few days into the visit, we asked why he
wanted to come to the US specifically: 'to improve my English'. Woops.
Away went the stack 'o books.. I guess the fairest thing is to trade off.