We had a carpet cleaner come and tell us that if he used his professional chemicals, it would mix bad with the urine residue that we didn't get all the way out of the carpet. He said it could cause some serious breathing problems for the kids. He also said that the amonia left behind was attracting dirt. Almost all the dark spots on my carpet were little splatters where we didn't clean up the dog urine well enough. Anyways, we used a steam vac on those areas and they SEEM to be totally fine now. I still need a professional cleaning tho-how can I tell if the carpet is clear of all that nasty urine before I waste more time calling him out again? We spot cleaned, but apparently that didn't do a good enough job!