I was (at one point) fairly conversational in French by US standards (was taking 300 level French conversation classes).

Did a fairly long trip in France, using as much French as I could. The speed of native French speakers meant comprehension was hard but manageable, and they seemed (almost intentionally at times), unable to make anything but what I would consider "travel French" work. I was fairly discouraged. I then met an Italian ski instructor who worked in France, and I could understand him quite well, and talked with him at a level (job, hobbies, family, reasons for travel) that I never achieved with a native speaker.

It was one of the most memorable moments of the trip and really gave me a feeling that we're all "citizens of the world" and not quite so divided by culture and lines on a map.