From what I see in people around me also suggests how you drink it: with or without empty stomach, with or without milk, had a bit of oily meal or completely vegetable based meal, and so on.

Like Elizabeth Rust mentioned, in some healthier elder people who drink coffee tend to choose black or add a bit of milk instead of adding lots of sugar.

One of the Mexico ambassadors showed how much he drinks coffee a day. 5 to 6 (tea up like shaped) cups! But the color of the coffee wasn't dark at all. And what he ate tells a lot, I guess. Lots of potatoes with some good amount of oil.