Pet urine was so bad it soaked the sub floor and rotted it. 

With strong odors you may also need to roll the slab with killz, for dog urine ect.

I will say, just be thankful they don't have pets--- I had a similar situation, gorgeous redone house.. and in 1 month, they let their cat urinate all throughout the house.. the smell was atrocious!!  

Underneath the house there is a lot of junk, everything from broken cinder blocks and insulation to toys and cat urine.

What I learned after being there for 3+ years is that it was just like living in an Apartment as no-one knew each other and there were always people coming and going, lots of Parties and such and with the animals, a lot of the renters did not care if their animal urinated outside on the sidewalk, as they stated the dog had to pee.

The animal urine will seep into subfloor.

Chewed up doors, dog feces and urine covering the 2nd floor, and homemade dog kennels in one of the rooms!

I had to get in there with a hired hand to paint, shampoo the carpets and mop his floors to get rid of the urine stench before the appraisal.

Thinking things could not get much worse, we went into the basement and found that there were a number of cages filled with mice and rats that they used to feed the snakes upstairs . . . and it smelled like urine from the rats / mice.So here is the question. 

Has vinyl siding that is in OK shape but kind of a urine yellow color.