I could smell these people a few feet away inside, and presumably they smoked even before they got to my property.Won't the smell on them get on the furniture, washing machine, in the air?

They will either look at Air DNA data (short term rental) or they will look at long-term rental data and you can evaluate both types for aparticular property.  

On an investment property math is suggesting you take the money you would use to pay off the principal (presumably 75%) and buy 3 more (with 25% down).I always remind people that in 1960 you could have bought a brand new house from a builder (with automatic air conditioning!!!)

DiTrento: A friend of mine came  across this property called "The Burnham" in Nashville TN.it seems like you Lease it and they let you air bnb it.Looks like they take. 25% fee.Seems to be a pretty busy place and a lot of people stay there.Does anyone know about this place or places like this?

Tenants will still call the landlord first for emergencies inside the unit interior (ie appliances, air conditioning, plumbing inside the walls).Common area issues (hallways, roof, lobby, elevators, exterior doors, landscaping, heating, etc.) are HOA’s responsibility.It is preferred that the tenant call/text us first and we will call the HOA.

The kitchen and the bathroom were because of the original leaks before we bought the house.What we were dealing with is Aspergillus, Penicillium which I was told is in our every day air.

Rents and values are still below national averages and the local economy is supported by a large state university, an Air Force base that is growing in population and significance and a regional hospital.

No business can humanly exist selling say a loaf of bread on Monday at one value, and come Friday when they go to reorder items to produce more bread, 10% of the sale $ they took in has evaporated into thin air. 

If these are STRs, you can also use air dna projections on certain programs.The one question that comes to mind is when you mention 10% down.

Multi-Family, Air BNB, other?