While I have never tried to pay a kiosko in dollars, dollars are often quite usable here, especially boca a boca- we often offer dollars at flea markets and when buying quantity from wholesalers, and various other owner operated businesses. Usually a chain businesses wont take dollars, but many owner run places will, and will usually offer you a decent exchange rate. I have spent dollars on jewelry, furniture, and materials we use for our artwork. Lots of people want dollars. My wife sometimes exchanges dollars for pesos at a shoe store down the street, who we have known for over ten years, and if he has the cash, he usually will buy dollars. It cant hurt to ask. Although I almost never do it in amounts under multiples of $100, as I dont carry wads of ones and fives in Buenos Aires.