The only annoying thing with Airbnb is any money collected after the booking (payment requests for upgrades, pass-through taxes, etc) are deposited into the master account, which is very annoying.

Added a second full bathroom, upgraded light fixtures, paint, kitchen counters,appliances, roof.

However, they could turn that on your liability if their doesnt exist blaming the property itself (maybe they got hurt by a hole in the yard, or a broken fence).

You can choose to ignore the costs for 20 years, but from an accounting perspective, it (pretty much) all works out the same as figuring $1000/year.And that doesn't even include things like siding repairs/replacement, major plumbing upgrades, major electrical upgrades, etc.

Easy to find, but also not sitting in plain sight to passers by.I thought if that box was broken into by a vandal or thief they wouldn’t be able to gain immediate access to tenant units if I only put the outer door’s key inside it.

Otherwise, you could upgrade for one month, download the package worth $100, and cancel your memebership.

It's almost as if the people who lived there had recently upgraded the house, weeks before it was foreclosed upon.

Sounds like you spent significantly money repairing and upgrading the properties and Airbnb dumped you for how the properties were BEFORE the upgrades.  

Do the repairs/upgrades.  

Anyone provider who comes to your house will tell you how it should be done "by today's code", but that doesn't mean that you need to upgrade now or even in the near future.