Thinking of walnuts specifically, sometimes they can have a somewhat bitter aftertaste and I'm not totally sure how that would come through in a nut cream or a nut cheese.
Yes, it was a struggle to keep the shark down in the presence of fiercely nationalistic Icelanders, but when I tried it, the hákarl was actually somewhat sweet and initially there isn't much taste... it's the aftertaste that lingers pungently.