I have great difficulty distinguishing between formal and casual with a lot of fragrances.
Scents like Bois du Portugal and Tauer L'air du Desert Marocain, I've only really reached for when I'm going out for dinner, black tie functions or special occasions etc.
So many though bridge the divide, and I guess it depends on what type of person you are. For instance, I don't tend to wear sweats other than at the gym, and i'd certainly not reach for those two when i'm about to hit the treadmill.
But equally, I am happy to wear them to work wearing a suit and tie, or to go shopping wearing a polo and jeans.
Most if not all in my wardrobe, and indeed those in my sample box are reached for on "formal" and "casual" or even "night" and "day" wear in equal measure.