ive actually got a rug in my shed, it was a friends, i cleaned her carpets and she asked if i could get the smell out of the rug for her, had a few goes with no success so she said i could have it to see what i could do, also did a flood job in a pub, when i got there it smelt (?) of wee, couldn't rectify it which i usually can. it obviously wasn't wee so i'm guessing its the same prob. so far (touch wood) ive never actually triggered the smell.
if anyone wants the rug (allthough its been in a damp dirty shed for a while) there welcome to it for research.