The only instance I can think of where a building's presence would lower the value of the land to an investor is if the building was in such bad shape it had to be demolished. 

If the subfloor is in rough shape or way out of level it could end up higher, also most installers will only give incremental pricing on 500sqft or more

There aren't a lot of times I can point to a 12 month trend where 7 3-family properties "just like" this one went to market and sold.  

These go down to a U shaped connection into the line. 

I'm not sure there's enough room to make a profit for the owner, for you, and for an investor.I assume you mean the house will be worth $100K once it is restored to great shape. 

The duplex is neat because it's an L shape on a corner lot.

Keep in mind that the trend graph looks like a straight line if you connect the start point and end point directly, but the market does not behave in that straight-line manner; so the connection is made with (potentially multiple) sinusoidal shapes that will go up and down within one cycle of the sine wave.

Tub looks in decent shape so that should save you couple bucks.

The ones that are not really run down but in good shape are too much compared to the income it generates.

The Long Term Trend Line for That Market?