Adding sugar to a glass of juice that already has crystals at the bottom does not make any sweeter?

Adding sugar to a glass of juice that already has crystals at the bottom does indeed make the juice sweeter. It is possible that due to the low temperature of the juice the sugar that was already dissolved in the juice has recrystallized. However, once that the sugar is added, if you mix it well with a spoon or stir it, it will dissolve completely in the juice. This is regardless if the juice had previously recrystallized sugar.