It's bad enough that grandma is getting out of it after all these years so you need to be prepared to kick these tenants out immediately, clean the place up, and then find new tenants.

Other option is to have ducts cleaned but will it solve the problem?

They may decide to buy $60k worth of ugly carpet for the entire building, or they may decide that it's okay to leave the old carpet and it stinks from dog pee.

Another thing to consider is vacancy rates, well priced, clean units in Los Angeles rent very quickly.Hope that's helpful.

You would have cleaning, repairs, restocking and policing to do every day. 

.), Wi-Fi, and obviously convince if I need to clean or fix anything in the unit.

Go back to your REIA you now have direction and find someone/ a couple of people that is doing that strategy and add value to them (I don't care how heck offer to clean their job site for free). 

I have a contractor (who doesn't know ADU law), a PM and cleaning crew lined up (I own other properties in The City, and have done VRBO in other houses, so I know those issues).

I have had great results from using these sources and get tenants who pay on time, keep the property clean and report needed repairs responsibly.   

Besides lost rent, you got to re-paint, re-carpet sometimes, and major fix-up if the tenant is a slob.