Like promathia said, it is the EM event drops. Im at work now but off the top of my head i know.
Almost every painting from a EM event is non turnable; a scrap of memory torn from the mind of charlotte, the crux an picture, a tattered sho from rondorin empire ect, ect..
And then a bunch of other EM event item;
Rangers Garb
the Unfinished Timepiece clock
a toxic potion of a verulent rose
A golden mechanical songbird
A bronze shield replica
a bunch of the sword display event drops.
All of the Hanging axe/sword type of drops, like the new Vlad the torturers torturers tools
Also the new stealables from Eoden i think all are not turnable. I know for sure the carved myrmidex glyph and lava rock. But i think all the others aswell.. the old ruined paint stealable to can not be turned.
I know it is a very small thing in the grand scheme of the game. But for collectors or anyone who deco's its a tad bit annoying. when you pick up a item to fill a certain part of your house and then you cant use it bc its not turnable.