It is important to pay attention to food lables and ingredients. A good example is Naked Juice.
The label clearly shows a high amount of sugar, 28g for only 8oz of juice. However, if you look at the ingredients label, there are no artificial sources of sugar.
One must read the ingredients to check of the sugar content is artificial, or due to the natural sugar content of fruits and vegetables.
The FDA has made this more clear in recent times, as it can be seen that some labels now show the difference, as seen in this comparison.
It even shows the percentage now, it did not do that before.
Notice that 10g is 20%, it was stated earlier that the absolute maximum added sugar one should have daily is 50g.