Is it impolite to ask for a dogie bag at an expensive restaurant?

It's generally considered acceptable to ask for a doggie bag at an expensive restaurant, especially if you have leftovers you'd like to take home. However, it's important to do so politely and with an understanding of the restaurant's policies, as some fine dining establishments may have specific practices regarding food to-go. If you're unsure, you can observe the behavior of other diners or ask your server discreetly. Overall, as long as you approach the request courteously, it shouldn't be seen as impolite.