Does what's under the house matter?

[Zack Miller]

My friend and I purchased a double this past spring in what was the first deal for each of us. Its not gteat but it cashflows. 

We are currently remodeling one side and have and questions about if what is under the house matters. We basically have a manufactured home on top of a basic foundation, footer and a half dozen rows of block. Underneath the house there is a lot of junk, everything from broken cinder blocks and insulation to toys and cat urine. It's gross. We don't have a good way of cleaning this out, we'd have to rip up the sub floor, but wondered if it's something we should do. 

Any and all opinions appreciated. 

Zack