The other magic ingredient is salt. A tiny pinch of salt can balance out sour and bitter flavors in surprising ways, and be otherwise undetectable. I’ve “fixed” a lot of cocktails that way.
Like bad and maybe salty?
Takes a minute before they track it down. They'd mixed up the salted ice cubes they used to keep champagne cold with the ones they use for drinks.
That one was rough. I had politely worked through my drink before we launched the investigation. Good party though and I did get a new drink which tasted fine.
I'm sure a tiny pinch can do wonders. Salted cubes, not recommended.