I am not going to disrespect the child slaves harvesting coffee by putting pumpkin spice into it.

Hadn’t heard of it, but now I’m interested to give it a try.

Not specifically, but my sister's boyfriend is Syrian, and apparently they put cardamom in their coffee. It tastes amazing but should be enjoyed without milk.

I've enjoyed coffee that was roasted with cinnamon. I've mixed in cinnamon with ground coffee myself (in the upper part of the espresso puck only) for a similar effect. Tastes great. Would recommend.

I've had coffee with orange juice, which was weird but ok.

As long as you mix in good ingredients, you get something good, that individual taste would judge if it's likeable.

After all, what's so objectively likeable about bitter bean juice in the first place?

Sounds interesting, similar to Arabic coffee. Also I see more and more drinks at local cafes experimenting with sour/bitter tastes. Such as coffee kombucha or adding orange juice/ginger. I was skeptical at first but it is really nice as an occasional drink.

I've added chicory before, sometimes a LOT and it's an okay flavour. Still prefer it black. I've had it infused with blueberries and actually that kicked ass! Will try mulled coffee sometime soon, thanks OP.