There are poop, urine and blood droppings all over the garage.

It's very hard especially in California where Pot is legal. 5 out of 10 applicants cant pass a urine test, and the other 4 had some sort of traffic violation on their record within the last 5-7 years.

No house was built to take large amounts of urine.

Notify the tenant that you are coming to inspect because you have reports of dog urine from the downstairs neighbor and you have pictures of the damage.I'm unsure how urine would get inside the wall.

Is it smoke, dead rat, urine?

It's not as bad as it initially was but my guess is previous tenants were in there smoking for 20+ years and maybe not just cigarettes, plus there was dog urine as well....We have replaced drywall in some areas, skimcoated and painted, new textured ceilings, pulled out carpet, replaced floorboards, put down new lion boards and new LVP flooring, new paint, all new appliances.

I was just complaining about cat urine in the carpet at my rental after walking it with the cleaners.

On larger sites you could have porta johns every floor and still find 100's of urine bottles in the walls as well as food thrown in the walls and other stuff. same goes for residential construction.

Tile is not great either because the urine will get into the grout joints (yes, even if they're sealed) and you'll have to regrout.

You got past the first big hurtle in real estate investment - signing up and reaching out in BiggerPockets.