Michael (Michel?), there's also a very significant difference between Canadian and Parisian French; we have a lot of Canadians vacationing down here at the shore so we often hear the former, and our sailing club at a nearby lake has a lot of French members who have come over, with their families, as executives in the local glass companies. The French are quite disdainful of Canadian French, being such purists, as you suggest!
I once worked with a French fellow and tried to practice on him, and of course he couldn't tolerate it. The French people at the sailing club are fine about it but we rapidly lapse back to English because my conversational French is so rusty.
We had a French adolescent staying with us for a month when my kids were young teenagers and it was a nightmare. The kid was a real behavior problem, put salt in a cake I was making, and broke both our toilets, but because he refused to speak English (which was supposed to be the point of the cultural exchange, of course) my French really got good for that period. I've always had a good accent - which doesn't mean I always know how to pronounce the words. But a high point was the time that a French guest of one of our resident French colony came paddling up to me at the lake and asked, "Quelle heure est-il?" and after I told him the correct time in French he asked what part of France I hailed from. Wow! I could rest on those laurels for a long time... Another time I was sitting in a group of local French people , following their conversation and making occasional comments, when one of the women suddenly looked at me in surprise and said in French, "But you're speaking French!" I don't think she had realized before that that I could, so that was fun, although the attitude was almost akin to the amazement that would be engendered by suddenly realizing that a dog was addressing you in human speech. Still, I certainly couldn't sustain it for any length without lots more practice.
Otherwise the French seem determined to shame us into speaking English because we can't possibly approach their standards. Seems to be your experience, non?