I noticed something inconsistent with Photoshop CS6 (current version I use at work). When you have a design on its own layer (not the Background layer) and scale it down, say 50%, using the default scaling options, it will create 1px semi-transparent border. But, if this same design is flattened and the Background, it will scale with a clean cut edge. The example image shows the top method being clean cut while the bottom method shows the 1px semi-transparent border. I believe the top method is the correct consistent approach.