Glycerol is the third greatest byproduct of the fermentation cycle (ETOH and CO2 are the first two respectively). Now, since dry red wines tend towards higher ETOH content than do dry white wines, which do we think will tend to have higher glycerol content? Also, it seems there is some inter-play between phenols and glycerol in providing mouth feel and perception of sweetness. Again, red wines have higher phenol concentrations than do whites. As we know it is red wines that receive all the attention for health benefits too. Here is a study that posits the glycerols are the key to these benefits: http://www.clinchem.org/cgi/content/full/52/4/785 Again, I could well be wrong but my very limited knowledge tends to indicate I am correct and your hypothesis of residual sugar being more important for the perception of sweetness in red wines than white could possibly be incorrect. If you want good examples look at CA Zins or Oz Shiraz. High ETOH, tons of fruit, clear perception of sweetness usually. Either way, wine is good.