Eminem is all about blurring the distinction between reality and fiction, humor and horror, satire and documentary, so it makes perfect sense that The Marshall Mathers LP is no more or no less 'real' than The Slim Shady LP. To Eminem's credit, he decided to exploit that confusion on his masterful second record, The Marshall Mathers LP. Many dismissed his considerable skills as a rapper and social satirist because the vulgarity and gross-out humor on The Slim Shady LP were too detailed for some to believe that it was anything but real.
It's hard to know what to make of Eminem, even if you know that half of what he says is sincere and half is a put-on the trick is realizing that there's truth in the joke, and vice versa.