I started adding salt to my ground coffee in the filter a few months ago, after a friend recommended it. It reduces the bitterness/acidity and I feel that the taste becomes smoother and richer, if you would. I've been adding cinnamon (a dash in the filter over the grounds) for years, and everyone always raves about our coffee (sweetness spice also counteracts the bitterness). Salt and cinnamon - not bad, as long as you are not watching your sodium intake. If you do, try just the cinnamon.