If you stencilled "No trespassing" onto the front door, and then repainted it when it was sold, that might do it.

As a landlord, you have to expect to repaint on some sort of schedule anyway (5-7 years?)

The apartments each used the same paint and paint color between move-ins and it was necessary to do a full repaint (one coat).

I know that Hardie board does look better and is very durable but it will require to be repainted eventually and this is quite a bit higher cost.We currently live in one of the units and rent the other out and plan to live there for the next 5 years or so, then move to a different house and keep the 2-flat strictly as a rental; I expect us to keep the property for a good 20+ years.

But over 25-30 years, I'll still have to replace again the roof, water heater (maybe on less time), repaint (maybe on less time) etc ...

It needs to have some of the siding replaced and repainted, the kitchen could use updating but not necissary. 

I've repainted and and cleaned the unit and the smell is still noticeable.  

From that perspective we think it will need and we will want the following:-From the outside the house the foundation looks okay- the owner said there is no mold issue- the porch needs to be jacked up and repainted- new flooring on porch- It doesn't have central air we would add- we are considering putting in different dormers due to a side of the roof sinking next the current shed dormer.

Everything needs repainting.

It only needed touch up but the prior paint was flat and it was advised that I repaint with semigloss to avoid similar wall paint cleaning issues in future.