I know some good DKs, but they have the fail stereotype for good reason. Lazy, bad players are drawn to it thanks to starting at lvl 55 and being pretty easy to play with. In the end, their quality or lack thereof is due to the player behind the character. It's not DKs that suck, it's that sucky players are drawn to it. Don't worry about it. If you don't suck, people will recognize that quickly.