Only chicken organs with a bad aftertaste IMO are livers. I think it's because the iron is a lot more concentrated than in say beef liver. As for spleen what does that taste like? I imagine you could make something similar to blood sausage with it.
Addendum: for hearts and gizzards I recommend boiling an hour, cutting them all in half post-boil and then frying with onions and parsely with a cup of the leftover chicken water until it reduces. Salt to taste after.