When you use a "clone" tool the pixels around of cloning point are being "pushed" aside in all direction.If you use a large brush size you will see distortion in pixels around.Then you have to come back from other side to "push" those pixels back.I am using a cloning tool a lot in photoshope or MGI and it is annoying.I wonder if someone wrote a "clone tool" what will clone a point of interest and placed it without pixels distortion.I am sorry ,but this is the best I can explain.