degree of saturation is the percentage of air v. water in the void space. It cannot exceed 100 percent, irrespective of whether the soil is sand or bentonite.
water content is the weight of water divided by the weight of solids. This can exceed 100 percent for soils, primarily clays (i.e., where the void ratio can be quite large) or for organic soils (i.e,. where the specific gravity of solids is very low). Water content can exceed 100 percent even if the soil is not saturated!
So, whether you are dealing with bentonite or not, the degree of saturation cannot exceed 100 percent.
I will agree that if you are reckoning a bad value for specific gravity, you could be calculating a bad number.
