I personally like using the ability to understand stand-up comedy as the gold standard of fluency. I've lived 10 years in France now, and I was already capable

I personally like using the ability to understand stand-up comedy as the gold standard of fluency. I've lived 10 years in France now, and I was already capable of doing a job interview in French on arrival, until recently I only had French friends, only watched films / tv in French, read books in French 90% of the time, and I still struggle with comedy. Part of it is that they speak so fast, part of it is cultural references which I don't have, but a lot of it is that nuance is a major part of the comedian's trade, and I'm more or less nuance tone deaf, even after all these years of effort.