A certain bikeshop fitted a new headset and forks to a frame of mine. Two weeks later a couple of crimps started appearing at the front of my headtube, one at the top, one at the bottom. These turned into small cracks at which point I took it in to Chas Roberts. He said it was because the headtube hadn't been reamed properly for the headset. A lot of stress going through that part of the frame. I would always get it done properly now as it is cheaper in the long run.
Name & shame!