There is a chain of Grocery Stores here in Phoenix called Food City which caters primarily to people who speak spanish. They have a variety of Mexican foods and most products are labeled in Spanish as well as English. Most people there speak spanish- however I heard a commercial on the radio featuring the fact that they don't only speak spanish. So I finished my ultimate frisbee practice and didn't want to drive to Trader Joes so I stopped at Food City, I got some cheap grapes and strawberries and some Coconut Ice Cream (hecho en Mexico!).
Whenever I'm in a predominantly spanish speaking area or store, I use what spanish I know to communicate. So I did the same as I arrived in the checkout lane asking "esta cerrado?" (is it closed?) when I got closer she asked "How are You?" in perfect English, I responded "just fine", more than a little bummed that she didn't want to speak spanish with me. For me that's half the fun of places like that, but oh well.