WARNING- Could be offensive to your morning
Dark Coffee is just burnt coffee. Let’s face the beans aren’t roasted a bit longer but are burnt. The same way that one grills a steak on the BBQ too long and you eat a bit of the ashes. You can say the bitter taste is those ashes. The hard truth then is if you really like the taste of coffee not ashes then you should have a light or medium roasted cup. If this offends some of my coffee lover friends well then add some milk it always tastes better with ashes.
FOOTNOTE- This should occur with Chocolate as well with light roasted cocoa beans being at the top of my list.