by mastermindcontrolI see this "filth" as not a dirtiness but as a retreat in to the underground. to that place where the wicked live and the twisted thrive. I think it means that how ever well integrated any socio/psychopath is into society and how sophisticated, intelligent, and cultured they are they will feel the urge to satisfy there "dark" side.
Ah, well, in that case I've had a vacation in "filth" quite a few times in my life.