I've tried natures miracle, resolve, and some other stuff. None worked very well and I was about to tear out the carpet. Then I bought a couple big bottles of a commercial cleaner made by Zep from Home Depot. I used a lot of this stuff - pouring the entire bottle into the carpet rather than just "misting" the top. It worked great!! Another cleaner I found that works well is one they sell with the rug doctor rentals at the supermarket - not the cleaner for Pet Stains but the one for Odors.