The stain resides in your padding under the carpet. You can clean the carpet all you want but to fully remove the stain you will need to replace the padding. Next time you're buying carpet look into 'pet proof' padding. These products have a moisture barrier on the padding that do not allow stains to penetrate. When you clean your carpet, the stain comes up 100%.

Yes. Six years ago we also bought an expensive smartstrand carpet with top of the line padding. We are far from satisfied with it. It has been very difficult if not impossible to remove any stains and in that regard does not compare with scotchgard carpets. Even after yearly professional cleanings, traffic areas look like trampled dirty traffic areas. We can't wait for an excuse to replace it.