That salt trick actually makes sense if you get the amount right. Too much salt and your coffee tastes like the ocean, lol. I've tried it with a tiny pinch, like three grains per cup, and it really smooths out the bitterness. The salt stops some of the bitter taste on your tongue, so you taste more of the coffee's sweet parts. It's a big help for cheap beans that are often sour. Just don't use too much, or you'll need to throw the whole thing out.