I spent two years living in Germany, about a 30-minute drive from the French border.
When my coworkers visited France and spoke English, everyone was rude to them and refused to help them. When my wife and I went to France and attempted to speak French, everyone was super nice and helpful... but would immediately switch to English for us.
We learned that as long as you made an attempt to speak their language, the French were very accommodating. But they'd get offended if you just assumed they spoke English.
My wife actually got frustrated because she wanted to practice her French, but no one would speak French with her. Except for the Germans. She tried to speak German to a guy in Berlin once and he switched to French for her. Turns out, my wife speaks German with a French accent. She was able to successfully complete the conversation in French.