THE SUES. JESUS THEY ARE EVERYWHERE.
No, seriously. Any time I do a search here on deviantart it pulls up OCs. Now, I realize that on a site dedicated to people making art that of course this is going to be a place where people are going to present their OCs. In fact, I have done the same thing myself with Artemis and Musashi. However, this is where Sturgeon's Law comes into effect. Almost every OC that I have ever seen here has been either crappy, or a Mary Sue. I don't mean in terms of art, I pass no judgement on people that aren't as artistically gifted as others. Hell, most of the stuff in my own gallery looks like crap. XD But in terms of the character and the information they give about them is just...crap. It's all very vague. Not to mention that they run around with absurd powers such as an invisible armies or violating canon laws of physics in the universe. Why? Why would you want to show everyone your poorly developed wish fulfillment? It just seems sad to me.
If you're going to put an original character of yours up on DeviantArt, it should be one that you've put a lot of thought and time into. The best characters are never the most powerful, they're usually the most flawed. In fact, some of my favorite characters have been amongst the weakest in their respective series. Not to mention that flawed characters have a lot more room to grow and change, which makes them even better! A character should never be a fully-formed, functioning person with crazy-ass powers. They should be a person trying to survive, dealing with their own problems and trying to find their own happiness. I can understand why not many people do it, because its a very difficult thing to make a weak person. We don't really want to be reminded of our own frailties, so we make these almighty personas that we can turn to and feel comfortable in. But a real OC, the ones that we remember, are the ones that not only we enjoy RPing as, but also teach us things about ourselves. The RPer usually makes a character a kind of person that they admire and want to be in some way, good or evil. What most don't realize is that we have the potential to become that kind of person if we really want to. That's probably the real reason that I can't stand Mary Sues. Because they're a stagnant existence. They don't change, and they don't teach you anything about yourself, other than you want to be someone else.
I guess if I really boiled it down, then my thoughts are that Mary Sues, by being wish-fulfillment, actually don't fulfill our wishes at all.