As a designer, you often don’t have access to the resources you need. The client doesn’t provide a hi-res enough picture, you didn’t get the photo from the angle you wanted, etc. Sometimes, it’s just laziness of photoshopping something instead of just taking the picture yourself. My favorite is when your boss thinks that Photoshop is a magic tool that can do anything, add or subtract people and objects at a whim, etc. Whatever the reason, people have to do this crap all the time. Here is when Photoshopping goes horribly wrong.
When looking at these, I’d like to say one thing. From my experience, don’t blame the designer, he probably didn’t have a choice. Link