Best non-food consumable items are probably some type of teas and tisanes, I also like snacking on coffee beans. Best non-edible items are paper and pencil lead, blood also actually don't taste bad.
I have so many worst ones. The one I am disgusted the most with are mostly animal body parts (skin, fat, tripe, intestine, dark meat of some fish, etc.). The one I cannot bear to taste is probably some herbal medicine, they have distinctive bitterness.
Dragon fruit adds beautiful color to your juice, yoghurt, and salad. It also adds antioxidant and fiber. It is the type of food that is better combined. I agree though, they taste the blandest they could be, especially compared to their appearance. That could be an insult, "You're dating that guy? Ew, he is a dragon fruit."