Originally Posted by RobWalker
I read somewhere that refined sugar causes massive hangovers...
Refined sugars aren't going to cause hangovers. Poor fermentation temperatures will cause fusel alcohols and other products that give worse hangovers, as can lack of overall nutrients in the ingredients, just due to extra stresses on the yeast producing less predictable chemicals. Adding yeast nutrient is pretty good practice for making wine or cider from juice though, so relying heavily on refined sugars doesn't change much there.
Where refined sugars (dextrose, white sugar, HFCS, etc) differ is simply in that other flavors have been purified out of them. This means that they boost alcohol content without any real flavor contribution, as opposed to adding honey/maple syrup/molasses/fruit concentrates which boost ABV and add additional flavors. I have heard people claim that sucrose/fructose based sugars will give a fruitier flavor than pure dextrose, but if so it's very subtle relative to the other differences.