I do keep a log, I also installed camera inside in case he comes back.

Had it camera ran down about 300 Showing me where the blockages were happening, and how deep.

With no hiding spaces.Code type locks so only renters can get in.etc..Also coin free payment system will remove the temptation for local junkies to try to pry open the coin boxes.And a monitored camera system may cut down on locals trying to use it for a Marijuana smoking den.https://stealthmonitoring.com/security-blog/tips-for-securing-your-multifamily-residential-laundry-roomAlso know that washing machines cannot be in below freezing temps, so you will need some sort of climate control as it snows in Los Angeles.https://www.youtube.com/watch?

When the houses are unoccupied I keep a security camera facing the entry door and the HDTV.

Catching them on camera whining about how some greasy "investor" screwed them out of their perfect move-in ready home would be a plus. 

While showing him where the leak was in bedroom he pulled out his new infrared camera and showed me how it works.

I would recommend a front door camera, a camera that looks over the front driveway/front street area, & cameras by any gates leading into the back yard, but none in the rear yard.   

I bought a camera a couple months before my first property that cost about $1k.

They brought in a camera and basically pushed it down the line until there was just backed up water and it became black on the camera.

Just sat with a service tech from a plumbing company and watched the video from the camera they pushed down the sewer line in a 4 family property.