@Scott Trench as far as those cats, hopefully you are inspecting to make sure they are not urinating in the property.

When he flushes the toilet, often his toilet is overflowing and urine and feces liquid is coming through the ceiling through the bathroom fan and dripping all over the toilet and the floor.This has happened and been documented 4 times, that I'm aware of as certainly it happens when i don't happen to be here. 

There is pet urine and feces throughout our home to the extent that we are going to need to replace multiple baseboards and some sheetrock and all the carpet in our home.The garage door has been backed into and knocked off its track and broken.The landscaping in the yard is completely dead, driplines and sprinklers have been chewed off by animals, I have liens on my home from unpaid utilities, and Mario didn’t even know that his sub-tenant moved out of my home.

The cat urine probably soaked into the concrete.

My first thought is that the house needs to be gutted and rebuilt because that's the only way to get rid of the pervasive aroma of cat urine and ammonia.

Pet urine will seep thru the cracks in the flooring, and saturate the under layment.Ceramic tile, the grout gets soaked the urine seeps thru and saturates the under layment.Concrete the urine saturates into the cement and it's terrible.You will never win and damages may not appear for a period of time.   

Kilz has been a god-send for sealing in (or out, I  guess) pet urine odor on baseboards and subfloors under the carpet we removed (disgusting)...wondering if anyone else has proven remedies for getting pet odor out, particularly in stairwells (formerly carpeted).

I don't really see the money as a bonus, I see it as a quick compensation for damage likely to occur.One time we followed up on a plumbing issue, and found cat poop (and the most horrible cat urine smell ever)  on the stairs-- and I said "well, the cat has some fecal problems because I can't see you not cleaning up feces"  and the tenant (who we evicted) told me "oh no, I saw it, and meant to clean it up" ... 

When I had my handyman get it ready to rent again we discovered that the cat had urinated on the carpet and it cost me as much to clean it as it did to put it in when I renovated it.

They often pee to mark territory and their urine is much more concentrated than dogs.