The lesson learned is vetting the potential buyers before pulling the trigger on the one that might look the best on the surface.

However, since you have loans on two properties, you'll want to check with your lender about any due-on-sale clause that could be triggered by transferring the properties into an LLC.

Can you imagine an injury occurring where the judge/jury think your property is responsible but you are not? 

I've kicked around installing AC but still manage to get renters applying to live there before I pull the trigger on installing AC. 3 - 2nd Duplex - I installed central air after purchasing the property for inherited tenants but they've used their own W&D units for years.

One more tip – people remember stories that trigger their emotions.

There is an unfinished basement which will likely be permitted to convert into an ADU but might trigger the installation of a fire sprinkler system ($30k).

As mentioned above it depends on the metro but I would make sure I was comfortable with the LTR rate before pulling the trigger on an STR. 

The risks, such as triggering a "due on sale" clause and complicating your taxes, often outweigh the benefits. 

@John Bertolon we’ve noticed over the years that any decent rent increase triggers “stupid-trip” repair requests, change of owners or not.

Which CAN trigger the due on sale clause.