Hi , These have been bugging me for a while. They seem to be marks of rising dust and the clearer patch is where a calendar normally hangs but I took it off for the photo , probably needs to be there to help cover it up ! We changed the radiator a year or so ago , which explains why the grill pattern don't really match up with the wall stain pattern. I am loathed to try painting as I don't want to paint the whole room. Any tips ? Thanks in advance.