The basement had been clean and dry, but apparently encountered a moisture problem over the summer and now the back sides (all exposed particle board) of the cabinets are covered in green and white mold.

Temperature variation across the length of the planks is probably contributing, an inadequate moisture barrier underneath, the contractor didn't seal the ends of planks near the door, or maybe there's not enough of an expansion gap between the walls and the floating floor in that area. 

Putting what Patrick said a little more gently there is not any “low hanging fruit” anymore, no easy money.

The moisture  collects there and rots the log.

Maintenance seems like it would be lower than other properties as the tenant base is far more gentle on the property than an average person would be (from what I saw touring the property).  

If needed, we send a gentle reminder and that usually keeps them on their game. 

Look for evidence of moisture on the ceiling, especially along corners and look for ice dams or evidence of ice dams (shingles will be torn/dented) 

But I'm having a hard time estimating the cost of repairs like uneven floor joists, drywall install/removal of plaster, moisture in basement, electric, plumbing,  etc. 

Below are some generalizations about ongoing maintenance costs: Older properties require more maintenance than newer properties.Composition roofs require more maintenance than tile roofs.Properties in climates with hard freezes require more maintenance than properties in milder climates.Properties in locations with a lot of moisture require more maintenance than properties in dryer climates.Wood siding requires more maintenance than aluminum or stucco siding.Properties with lush vegetation require more maintenance than properties with little or no vegetation.Below is a typical Las Vegas single family class A home.In summary, I believe Las Vegas is not only a good place to invest today, it has a high probability of continuing to be a good investment location into the foreseeable future.

But this house is up on stilts and the dryvit doesn't have contact with the ground, but she says that moisture wicking is still an issue around doors and windows.