Think about it from the other direction -- how do you sell a $1000 mattress for $2000? 

If you send every dollar you make to pay your mortgage, put it under your mattress in cash, or lose all your income at the casino, that income is still taxable. 

I have a house like this and people will find a way to get mattresses and furnuture up there.

What's a fair price for a queen size mattress these days?

One room was full of mattresses, another had personal possessions, the plumbing didn't work so they turned a room into a public restroom complete with poop all over the floor and needles were found throughout the property.  

And put some good matress covers on your mattresses because of that you won't need to replace as often as the couches.

We put air mattress on top and put them against the headboards, which we leaned against the wall.

Thursday night I go clean up rotting raw shrimp from kitchen floor and house is full of dirty clothes and old mattresses on floor.

The problem is that they left tons of junk - furniture, mattresses, and lots of other crap.

A 3% cap rate is so bad that I think you would be better just keeping the money in your mattress!