My ex-father-in-law felt that everything French was inherently better than everything non-French. And American culture was not French in extremis.
For myself, "That is so French." is not an encomium. It sums up the kind of Frenchness that makes my spirit cry, "Mon Dieu! my soul is dying."
Here are some of the things that are so French that it makes my ass pucker:
1) Talking, talking, talking in French about existence, fate, chance, or art
2) Croissants and other French pastry - flaky and dry with billions of calories yet not filling.
3) Jean-Luc Godard - makes no bloody sense
4) The Maginot Line.
On the other hand, here things I love:
1) Audrey Tatou and Edith Piaf