We only manage our own properties and don't illegally rent bedrooms so I have not encountered any corrective measure for this issue but I"m sure he is correct. 

You need to invest in security measures: cameras, 6 outdoor motion lights, better locks, needs new flooring, roof is 30 years old.

So even if the appraiser did use some of the 4 unit buildings to measure against yours the adjustments the appraiser would be required to use would throw the value off too much. 

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He measured the foundation, but the house had overhang square footage that was 400 square feet, roughly 20 feet by 2 feet.

That means I have to follow stringent guidelines with respect to advertising/marketing.

As of this moment, it's at approx 28% full (measured by volume/content).

Bring a tape measurer and take some photos of a kitchen or bathroom, for example.

This measures the annualized return.

I explained that I am taking preventative measures for my tenants and it doesn't damage the roofing etc.