Maybe not necessarily a duct cleaner but any type of service provider try scaring your tenants into pressuring you into performing more/unnecessary work?

This may or may not work but if it does it's much cleaner than making a partnership deal with a foreclosed former owner.

@Gary L Wallman Even if your home was powered 100% by coal, EVs are much cleaner as they are up to 5x's more efficient than an internal combustion engine.

I also don't look down south as it's harder to find services (maintenance, cleaners, etc.) and it's prone to flooding.  

These also let you check on the status of the lock, who opened it, when it was opened, and you can even lock it or unlock it from your phone (cleaners will forget to lock up sometimes).As to changing the pin, you can set up a bunch of different pins and rotate them.

It's so difficult to get cleaners to do the same job each time.

I wasn't able to get my cleaner in there because of their urgency.

Hire a great cleaner and you can easily self manage and save a lot on PM fees.

My cleaners have their personal access codes and I love the change log function. 

Common household cleaners don't work.