I used to hang out in a cheap diner when I was in my teens, and one of the waitresses taught me to do this. It seriously takes barely any salt to cut the bitterness of particularly cheap, over roasted coffee.
Now, we make our good coffee first thing in the morning, but I also keep bags of cheap ground crap that’s only around for a mid-afternoon caffeine infusion. I always drop a tiny pinch of salt in the coffee filter when I set it up to drip.
