Oranges taste differently based on their position on the tree. Oranges picked high on the tree are usually much sweeter than those picked closer to the ground. Oranges grown on the south side of an orange tree are much sweeter than those grown in any other location. The north side of the tree always produces the least sweet fruit. The color of an orange has nothing to with the flavor of the fruit.
Temperature is the deciding factor of a great orange.
Cool but not to cold produces the best fruit. Temple Oranges and Murcott Tangerines have so much sugar in them that they will sink if dropped in water. All other oranges will float. Unlike apples, pears and bananas, oranges will not ripen any further after being picked from the tree. Oranges are called seedless when they have five seeds or less.