Sweet potato is supposed to be very good for you (anti-oxidants and all that) but for me it is just too sweet and has a rather muddy taste.
I find kiwi fruit taste bitter, but that's a very personal thing. For me fruit crumble tastes bitter, but a pie made with the same ingredients is fine. I can't cope with chicory or campari because they are so bitter, but I love black coffee and dark chocolate, also partly because they are bitter. Weird.