Mudslinger is an old villain who appeared twice in the series. Judging by his name, it is probable that he was once a journalist for a newspaper, presumably fired for writing untruthful and libelous articles.
In the episode The Great Unwashed, Brit and Tiff were attending a party with Don Prima and were upset by the attention Jenny was receiving (on account of her new paint job and upgrade). Resolving to be the centre of attention as they felt they deserved, they hired the Mudslinger to destroy Jenny's new look and literally "muddy" her up. He succeeded in this, and Jenny was so enraged that she nearly destroyed him. He confessed that it was the Crust Cousins' idea, and broke down, saying that he had never even been invited to a party, and knew how she felt. Jenny, in response, kindly offered him her invitation, on the condition that he got back at the jealous Crusts who dirtied her up. The Mudslinger made good on the promise, using his ink pen to stain everyone at the party and proclaimed that the Cousins invited him, destroying their reputation with the popular people there.