All the fruit I have been eating from my trees have been excellent tasting and not watered down, this includes all my drops. The flavor and the sweetness, to a great extent, is variety specific although fertilization and watering is also a key component.
If you have a sweet variety, let’s say Pierce for example, and it is not sweet. It could be due to lack of maturity of the tree,too high a fruit to leaf ratio, not getting full sunlight, improper fertilization and perhaps the number one culprit of watered down sugars and flavor is over watering.
Simon