Not sure what I can do but seems I need some way to block the water from their roof or change my vinyl siding to something else.

It doesn't always work out that way.... for example, I'm a really good landlord (as I've found out just this year) but the thought of being a landlord makes me want to run straight into a concrete wall.

@Calvin Rankin if it was unpaid property taxes, it would be tied to the deed and that could block a sale. 

Depending on the region, painted concrete or tile works fine too.

I have 5 properties in the zip code of these duplexes and I have been in the neighborhood and looked at 2 houses a few blocks from these in the past. 

Other thing to not forget here is that ideally you are 'blocking' your central air to your 2 units you decide you are going to be installing these on.#3 - this is what we did with our duplex. 

Is it feet, yards, cubits (LOL) city blocks, water-meters, utility poles, sewer lines, or just plain up to the lender?

We have grown to love our new neighborhood; very stable, many long term homeowners on the block.

Norfolk is very spotty on crime rates - Ghent is upscale but surrounded by impoverishment, then the city goes into a pattern of good street, bad street, good street, bad street.. for about 20 blocks.  

It sounds like your property manager might be a block as well.