When I bought a duplex in Nebraska (for $18,000), the side we were moving in to was nasty, even to the point of the last people laying carpet over dog piles in one bedroom. When the tenant on the other side moved out, we cleaned the basement with scoop shovels. You really don't want to know what all we scooped out. Just let me say, it took 2 gallons of bleach and days of scrubbing after we finished scooping before I let my kids enter the house. It was a full month of cleaning before we moved in. But it in no way compares with the nightmare in that place. You'd almost want to torch it and start all over again.