Our house is from 1949 and since we purchased it in September we have experienced a myriad of unpleasant "fixes" by the previous homeowner. The latest can of worms I decided to open is in our master bedroom.
The wall facing the exterior had strange plastic seams and was wallpapered and then painted over. The 3 other walls are in relatively good shape. They are plaster. I needed to know why this wall was "smooth" so I pried one of the plastic seams off and yanked a chunk of the "fix" right off of the wall. It was thin particle board which had been glued to the wall. Nice. Along with that came many chunks of the plaster wall. It's a lovely MUSTARD yellow underneath. Delightful. I started scraping the glue off of the wall along with other loose chunks of plaster.
I have begun youtubing various plaster repair, but this seems like a unique situation. It is NOT just a crack, but it is also not a gaping hole. I'm not exactly sure where to start. I think we need to continue getting the rest of the glue off of the wall along with loose pieces of plaster.