It goes without saying that Photoshop is one of the greatest blessings to ever grace the world of memes. We'd be participating in a much more boring internet if we didn't have the power to manipulate images for humorous effect. Done well, Photoshop is an incredibly powerful tool. Done badly, it is also powerful — but in a rather different way. Crappy editing and effects may not be the most aesthetically pleasing, but they can make up for that with the level of amusement they provide.
More often than not, Photoshopping is a process that is meant to leave you with a finished product that has an element of realism to it. What makes its failed attempts so entertaining is the fact that they act like we should take them seriously. Technology can't make up for lack of technique, but it can make it even funnier. It's almost artistic, in a way.