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by semi-extrinsic 3812 days ago
> I find (black) coffee starts going bitter/sour if not drunk soon enough.

The litmus test of good coffee: is it still nice to drink once it's cooled down to room temperature? If it's undrinkable when lukewarm, it's bad coffee hidden by the fact that your taste buds don't work very well at 85°C. Same goes for people who drink vodka chilled to -15°C, it's to avoid actually tasting the vodka.