Coffee drinkers - sugar etiquette question

[Love51]

I drink coffee very occasionally, ordinary old fashioned filter coffee. People ask if I take sugar. I don't know til I've tried it, it depends how bitter it is. Should I know? How? Is there a bitterness rating? 'I don't know til I've tried it' feels like a fussy bugger response! Thanks

I usually don't take sugar if it is coffee+ milk. Black coffee, I rarely drink and if I do I go for 1 sugar. Espresso, no Sugar. Yeah. No logic. Sorry, I have been of no help

I'd ask for half a sugar, to take any bitterness away, but then not too sweet if it's not bitter, iyswim?

Ii understand. It's like salt..I despise people who pour a kilo of salt on food they have yet to taste (unless it's fries)

Thanks :)
It is bad manners to pour salt on food without tasting, isn't it? How do I get the world at large to extend this to sugar in coffee?