Philip K. Dick created almost a legend for himself of his disreputability: he built a palace of disreputability and moved inside it. At a certain level, I think he said 'You can't fire me -- I quit.' Even some of his most ambitious later books seem to be almost deliberately scarred by the inclusion of gestures, jokes, references that make them aliterary intentionally, as though he's saying 'Fuck you.' Or 'I don't have a passport into that world, but I'm free to do anything I want.'
A book as fundamentally literary as Flow My Tears, the Policeman Said -- very lyrical, very beautiful -- has moments where the surface breaks down into smutty jokes. In Ubik, somebody calls someone else a 'hobbit,' and it's this moment of self-loathing in-jokery that completely throws you out of the page, especially if you're trying to read him in a very literary context. And I think those moments of breakdown in the surface of his work are quite striking.