I look at coffee made for guests as hospitality, love & kindness. I expect them to drink it as they normally enjoy their coffee, without judgement. It should be a pleasure for them, education is optional, available on request only. I was totally expecting to serve an Irish coffee on Xmas day.
I don’t take it as a slight if they want to add adjuncts, including milk (which oddly, you seem to consider separate to an addition?).
The coffee I made yesterday was £56/kilo and my guests drank the whole 250g bag over 2 meals.
I wouldn’t offer a lower standard of coffee to anyone (unless they asked for something else, that they knew was on offer), in the same way that I would not serve a different quality of food, because I knew a guest typically ate pot noodle.
Even my Starbucks stalwart niece commented on the how much she liked the coffee and was trying to describe tasting notes. My sister, who has only recently started drinking coffee at all, asked how strong it was…how we all laughed when I told her 1.4-1.6%TDS…I’m sure they were laughing with me, rather than at me? :-)