There are two kinds of blood sausage. One is bigger and served sliced cold. You eat it on bread, like salami. It is pretty good if you don't let it warm up. The smaller ones are cooked like hot dogs and served warm. They are terrible.
Lung soup was cheap. The lung is shredded and in this grey soup. It isn't bad, it just was not good. But was cheap. The germans also eat liver dumplings. Not especially good either, although considered a delicacy by some.
I never found any of the raw fish stuff good. I got to spend a week in japan with all of the raw fish that I could eat with a stick. I never found anything that I would order again. Raw tuna is not terrible, but not great. In a week, I lost 5 pounds. It would have been worse except for the beer and noodles.
Haggis is really pretty good. Lots of flavor, texture is good. You cannot really tell what is in the stuff. You really don't want to know. It is much better than black pudding.
An interesting one from iceland is rotten shark. They are trying to rebrand it as fermented shark, but the way it is made is to put big pieces of greenland shark into a big tub and then let it sit for several months outside, after which you hang it up to dry a bit before you eat it. It is a bit fishy but not bad. I ate one small piece. Lol. It smells pretty bad.
But I am game for trying almost anything.