The trick to using the cloning tool (in my opinion) is to watch the placement of the little cross hair while you're painting with the cloning brush (after having defined the starting point with option/click). While you're painting, you'll notice the cross hair blinking on & off and that's the source for the cloning. It'll move in the same direction as the brush is moving, so if you see the cross hair heading for a part of the picture you don't want used as a source, stop and re-define the starting point (option/click). There are some tricks to using it that are explained in the manual, but I'm not at home so can't look it up for you. I much prefer the way Painter does cloning if I'm going to do large areas, but the rubber stamp does ok for little jobs. You can also use the lasso tool to mask a large area quickly, copy and paste to a new layer, then use the eraser tool to fit it in (set layer transparency to about 75%). When you've got it right, set transparency back to 100% and flatten (or merge) the layers. It's a technique I've used often and it works well for me.