The property is in Moss Point, MS, which has had a consistent decline in population over the past couple of decades, so I’m cautious about the long-term demand. 

That creeping moss on the back fence?

Quote from @Drisana Moss: This is a great idea and I would really get with the realtor who helped you buy the property to pull comps to see who is selling properties like this in the area for on a sales price with the ADU attached and detached.

Will they scrub the moss off the roof or mow the lawn?

Roof could be OK, once the moss is cleared you can walk it and look at the shape of the shingles.

@Elisabeth LernhardtReno had a large number of 1 and 2 bedroom apartments come online in the last few years.

Moss off the roof 2.

Garage (detached)Moss/Lichen build up observed on roof. 

Quote from @Nicole Moss: There is a potential DG  for sale in a rural area. 

If you are looking for an additional resource, I recommend looking into Wes Moss's work.