We added value by re-doing the whole house, installed vinyl floorings, rebuilt 2 and a half bathrooms, re-painted the whole house, replaced all the hardware in the house, installed new lighting, ceiling fans, re-painted the kitchen, and completely remodeled the upstairs.

Same as refrigerator or ceiling fan.

I have even seen twice city inspectors walk buildings for other issues that have illegal basement units and as long as unit looks like a legal unit (normal ceiling height and two egresses) they didn't even say anything. 

Other leak along 1st floor ceiling.

Be attentive to damp ceilings or walls, which could indicate plumbing failures.Structural issues are critical to monitor.

City had already approved a shear wall to ceiling but inspector dictated it go to shingles.  

Make sure to look carefully at the comps sold in the last 300 days to understand the ceiling of what you could get in the best scenario. 

The first property that I bought was 2 legal units and a non legal conforming basement unit with adequate ceiling height and 2 forms of egress.  

But additionally, is this an 8' ceiling, 10', 30' tall?  

Install ceiling fans in each room.