I recently had my living room skimmed. The house is around 80 years old and as such the plaster was in quite bad condition before. We had a professional plasterer around who skimmed over the old plaster in most places and only in a couple of areas did he go back to the brick work. The work was done in January and we left it a good few weeks before considering painting. Before painting a few hairline cracks appeared that I filled in with pollyfiller. However since painting these have reappeared (and more) and seem to go on forever. I have again tried to fill and yet again they have reappeared. Some of the areas around the cracks sound hollow leading me to believe the plasterer should have gone back to the brick work in more areas than he did. My boyfriend thinks the cracks are just due to the age of the house however I am more inclined to think that the plasterer hasn't done a particularly good job. We have a lot more rooms to decorate in the house so would really appreciate some advice to try and avoid the same happening again. I would also appreciate any advice on how to repair the cracks once and for all.