Ugh.  One thing I can't abide is a dessert wine that I would call nothing more than 'grape syrup'.  Few vintners are capable, primarily due to climate/location, not lack of talent, of producing a dessert wine with the requisite acidity to back up the sugar.  In most locales, while the sugar of the grapes is going up, the acidity is going down, and winds up grape syrup even with additional Sauvignon Blanc that might rectify it.   Think of it in these terms:  sweet and sour sauce for Chi