I was skeptical but i have to say that It does work but it may take a couple of applications. We had an old pee spot in the hallway that had been cleaned with a carpet machine several times previously but when it was humid I could still smell it. I soaked it with the spray bottle and let it dry - I could still smell it but it was not as bad so I did it again.

We also had a cat pee on the carpet under our bed just this past week (so it was a fresh spot). I soaked up as much as I could and then saturated the spot with the spray bottle. Let it dry and when I rubbed the carpet with my hand I could still smell it so I repeated the process. The second time I rubbed my hand over the dry carpet and did not get the urine smell.