When entering many yogurt stores in heavily populated Jewish areas, one is often greeted with signs on the machines bearing a Hechsher, with the implied understanding that the product listed in the certificate, is inside that particular machine. In the case of a Kosher-certified franchise, the reason behind this logic is that the company is compelled by agreement to use only Kosher certified products. However, most non-franchised stores use whatever brand they wish for whatever reason works best for them (i.e. price, flavor, convenience etc.). The display of a Kosher certificate often is not truthful as to the contents of the current mix being used, nor is a promise of such an establishment helpful in determining the Kashrus situation. In the same way that one cannot enter a supermarket to buy meat with a sign near it stating “Kosher”, one cannot buy the ice cream or yogurt without reliable certification on the store. In the case of a franchise, one should discuss this further with their own Rabbi for guidance.
Fountain drinks, such as Coke etc. are fine as they are enforced by their franchise agreement.
Icee drinks in the U.S. are certified Kosher and are also enforced by their franchise. This is true for Slurpee as well. For the current Slurpee list, please look at www.kosherquest.org or at the K.I.B. app.