A conjunction of the words shithole and dump. Usually referring to a location but can also be applied to persons or things.
As a location this defines a place so hideous, boring and/or inhospitable it will not suffice to refer to is by either a shithole or a dump - it is thereby a shitdump
In reference to a person or thing it is someone/something who/that is unsanitary, foul, wretched or otherwise inequitably loathsome.
Can also be used an adjective.
Location: Man this place smells like dog-ass marinated with fermented fish carcass - What a shitdump!
Person: Dude, I don't think that guy's bathed since soap was invented - He's such a shitdump.
Thing: That piece of "art" looks like Salvador Dali loosely defecated a sculpture of Andre the Giant - What a shitdump!
Adjective: That's such a shitdump idea; Benicia, oh that shitdump town in California?; What's up with that shitdump jacket?