I started off by using this on a patch of carpet that used to have a deep freezer on it. The freezer was there for 10 years and there was a square marking the spot. I can't really tell you what the stain consisted of, BUT I can tell you it's a thing of the past! I used the recommended amount of solution in the Dirt Devil Portable Upholstery and Spot cleaner and it was so much easier than a regular size steam cleaner. It was easy to use and very easy to clean as well. I also used it on my dogs favorite piece of carpet from when he was a puppy. I've cleaned it before but the stain always seems to return. It's been a week and I can barely tell where the spot was!! I'm glad Christmas is close I will be getting another for my brother and his new dog!