The seller will lose some rent, potentially incur costs to evict, possibly costs to clean out the units depending on your sales agreement.

Just be the absolute best host you can be for the first year -- communicate clearly and quickly, make sure cleaning is top-notch, make sure all amenities work (hot tub is hot, TV remotes have batteries, etc. etc.)

Like deferred maintenance, (bad roof, worn out water heater/AC Unit, warped flooring, water damage) etc, unpaid utilities,  unpaid taxes, a second loan, unpaid HOA fees, a bad pool, bad reputation, sometimes squatters, sometimes they were drug houses, and so on.

I would just excavate a few 2'x2'x2' (or larger if possible) spot footings, w rebar and Simpson hardware,under the house (you will want to take up the floor to make this easier to do).

They request interior pictures and a walk thru.The Upper duplex is a single unit with the kitchen & living room on the 3rd floor and the bedrooms on the 4th.  

I ASSUME you’re talking $400+ in extra expenses for providing water, power, sewer, gas, internet, communal area cleaning, and exterior maintenance.

Huge counterparty risk, I am just working through a scenario where a correspondent HML in the midwest got defrauded from bad diligence and their funding partner is having to clean things up.

(I would be floored if I was a current upREIT investor in the RE Gain Fund.) 

Does that mean the applicant had a clean criminal record or that the 3rd party wasn't able to screen the applicant?

Because Airbnb only makes money when the guest books on Airbnb.Hence, they want the price to be cheapest on their platform, so people book on Airbnb instead of elsewhere, and want their properties to be able to compete with hotel prices (even after cleaning fee and service fees).