Just wondering why that is..

I sold the left or right Eye of the Falmer & one of Cicero's journals to Tonilia and she just kept them forever.

The price of the Eye gradually went down and down so I decided to buy it back as a house decoration.

Am just wondering why some items like these stay in the merchants inventory forever... whereas I must of sold Olava's token to someone and have been to all the regular merchants and can't find it.

I don't know. I sold the Radiant Raiment Fine Clothes to Belethor on a toon some while back. It's still there. It's very strange....

yeah, that windhelm smith still has Queen Freydis' sword for sale (i didnt sell it to him tho, he asked me to retrieve it - guess he didnt need it that badly). Adrienne has had the Whiterun guards armour and helmet that i looted off that first dragon for the whole game.

certain items may persist indefinately even after they are de flagged as quest.