I'm working with Photoshop for a few years now, but I've always had this problem that I didn't really understand or found a proper sollution for, I just found some work arounds...
When you create a shape in Photoshop(especially circles,rounded rectangles...curves..etc), sometimes, especially after you transform it, the edge of the shape is not full pixel, crisp and neat. It's sometimes a bit transparent or something like that. It has some sort of default Anti-aliasing or something like that...can it be turned of? Is it good to turn it of? Why is Photoshop doing that? [in illustrator for example there is that option to align object to the pixel grid, is there something like that in photoshop?]
I know that at certain sizes and twitches this does not happen, but I'm wondering why does it happen and if there are any rules to avoid this...
I also know and noticed Fireworks does a better job for this kind of stuff, but for some stuff I just love Photoshop...
have a look at this screenshot to understand what I am talking about: