Cats require a high protein diet; their urine can have a significant odor and it is worse with an unneutered male cat that sprays to mark territory.

Threw the old couches, mattresses, dressers, general trash, diapers, etc into the swimming pool, ruining the plaster, smashed all the water turn off valves under the sinks and washing machine with a hammer, tub full of **** and urine, clogged with a towel, toilet pulled from the floor, stove and oven smashed with a hammer, etc. 

I have some ideas for solutions but I hope some more experienced landlords can tell me if I'm on the right track or not.First, a tenant who just moved out of my property has left the carpet smelling like cat urine. 

He had to serve his tenant an eviction notice, and so the tenant proceeded to urinate all over the carpeted floor throughout the entire house....I guess he just pushed his tenant over the edge by expecting to collect rent on time.I'm sure there a far-weirder stories from other landlords, but that just happens to be the weirdest one I know of.

I remember reading mice droppings and urine have some virus in them that can make people really sick.

If you could not remove all affected wood in the subfloor - sometimes not possible, if strong urine/fecal matter made it to joists - you should have sealed everything which could have been done in several ways - polyurethane everything; poly vapor barrier; painting & 1/4" subfloor on top of old floor; etc.2.

Or bed bugs, cigarette smoke, cat urine.... ok you get the picture. 

Pet urine on any surface that is allowed to sit is no laughing matter.  

Sometimes the plywood sub flooring absorbs pet urine/dog poo, mold, and whatever else that smells nasty.  

Most renovation mortgages are either refinances, purchase deals where someone found the property off-market (so no listing agent chasing a paycheck), or purchase deals where the house is not in financeable condition but for some reason all cash flippers don't like it.This cat urine smelling hoarder special, which was utterly disgusting, for example, no flipper wanted to touch.