My stupid carpet cannot be cleaned, what would you do?

Crappy carpet is the start of your problem, which isn't your fault. A bunch of people will probably freak out at this suggestion, but I know from experience it really does work. I had a dog that took 3 years to housebreak, and needless to say the carpet was filthy. I shampooed the carpet with a 50?50 solution of water and mr.clean floor cleaner (any scent will work) and then about 2-3 tablespoons of dawn dish soap. You can also pretreat the area with mr.clean for better effects. Not only does this knock out odors, there will be no stain left at all. I used this on a white carpet and it worked beautifully. Good Luck!