If you want to make sure that the oranges on sale at the market are sweet and juicy, simply ask the produce guy to cut one open for you. Any large store will do this. If the quality is low then pass them by, buy if they are sweet and juicy. I have noticed that if the price of oranges seems pretty low then there is a reason for it. You can ask the produce guy to do this with almost any fruit and they should be happy to help you. If you get home and the oranges are dry and tatsteless, simply take them back to the store and get a refund. Make sure you keep the receipt until you have sampled the fruit. I have never been in a store that will not do this. It might embarrass some people, but I am not going to pay for fruit that is inedible and you should not either.