I noticed this problem about a week ago in a town I was in, I was decorating my apartment with paintings logged back on after a while of playing football and they were gone. I assumed that someone stole them, after a while I joined another town built a house decorated it, and the same thing happened. I just assumed to give up and keep my house the way is is. (Note: My house doors are all locked.) I later built a farm and I had ladders to go up to the next floor. For the past 2 days all my paintings and ladders have been missing. I don't know if I is a bug, or a Griefer. Has anyone else of their knowledge have had this problem?
I had some ladders go missing in a farm... lift signs, too, both up and down, though it registered that I broke the down signs, despite not being online at the time. When a resident of my town was in the same farm the upper floor ladders disappeared on him while he was in the farm.
Regarding Paintings, I think since they are registered as entities a /butcher or some sort of command can make them disappear, to reduce lag. I don't have a clue regarding ladders though...mine have never disappeared randomly. As always, please correct me if I'm wrong.
Painting, minecarts and item frames are all entities, not blocks. A /butcher will remove these items.
Okay, Thanks I continue to watch my ladders to see if it is a resident of the town, I have a few suspects but no evidence of them doing it.