If the skin is coarse and the color is dull, the person may have been malnourished during childhood, resulting in weakness and lack of vitality after growing up.  It may even lead to heart-related diseases.
If the Neptune mount is sunken and less resilient with blue veins, the person may have weak reproductive and urinal systems and may have hormone imbalance. This kind of Neptune mount usually is seen on people who are struggling with serious illnesses.