A few weeks ago, my buyers closed on a home. The home had white carpets. Not off-white. Not cream. White. They were beautiful, albeit original to the 1999-built date. The listing agent had placed a sign inside the home, "Please remove your shoes. Carpets were professionally cleaned." There were booties. The carpet nearly glowed, it was so pristine! The home was winterized and had been vacant for nearly a year. The heat had been turned off the entire time.
In my initial phone conversation with the listing agent, she said someone had tracked mud into the living room, up the stairs and into the landing upstairs a few weeks prior to our arrival. She had professionally cleaned those dirty areas. ALSO, the sellers' had done the entire house prior to listing the home nearly a year earlier.

There was evidence of dogs in the backyard, but none inside the home. There was no animal smell present inside the home. Since one of my buyers was allergic to pet urine (I didn't know you could be allergic to pet urine!) and there was no evidence of any on the gorgeous carpets, my buyers seemed satisfied. We wrote an offer. It was accepted. We had a full-home inspection where the gas had to be turned back on. The inspector ran the furnace through a cycle. Everything seemed in order. We closed on the home a few weeks later. All was right with the world! Yay!
The day after the buyer moved in, I received a phone call.
"The carpets are ruined!" Seems the dogs had in fact used those beautiful white carpets as their personal urinal. You could probably hear the buyers' expletives aimed at the sellers all the way up in Canada.
Because the home had no heat for over a year, the smell had settled into the surrounding surfaces. The sellers, thinking they would resolve the issue while they lived there, had rented a steam-cleaner, not a professional cleaning service. The sellers had PAINTED over urine stains on the walls and trim boards with regular interior house paint. The carpets had never been treated for animal urine. The heat was turned off and the home vacated for a year. So when the buyers turned on the heat for an extended period of time, the smell was painfully present. In the sellers' defense, they were trying their best to clean the carpets. But best efforts did not mean "doing it right" (i.e. professional).
When the buyers had ANOTHER carpet expert out, he "black-lighted" the floors and saw massive evidence of urine on the walls and basically all corners of the carpet was covered. The good news: The carpets could be cleansed to habitability with proper chemical treatment, but my buyers were extremely disappointed. Because the buyer is allergic, they must eventually replace the carpets at the buyers' expense sometime in the very near future.
If you are an owner with animals allowed inside the home, USE A PROFESSIONAL to remove the damage to the carpets. Or replace the carpets altogether. And ignorance does not placate an upset buyer once they buy a home for hundreds of thousands of dollars and find out it will cost even more money to fix a previously unknown (in my buyers' minds read: "hidden") issue. They were/are not happy campers.
My recommendation to any Realtor representing clean carpets to the public: Document EVERYTHING!! If your seller says they had the carpets cleaned, get their receipts. Even if it is the rental of a carpet cleaner from the local grocery store. If they used animal urine-remover, document it. A helpful hint might be to walk around the house with your own black light if you feel there is a presence of animal urine (black lights are inexpensive and show chemicals undetectable by the human eye). That smell is extremely off-putting to potential purchasers -- usually meaning replacement of carpet is coming. But without heat, odors disappear -- until it is too late (i.e. AFTER closing). And you may have some unhappy buyers on the other side looking for answers you may not be able to answer. Unless you are willing to step up and replace the carpets at YOUR expense, goodbye referrals. Use your best judgment when dealing with carpet issues. And never, NEVER trust the WORD of a seller. Not that the seller is lying. They simply may not know any better. You just want to cover yourself for future issues that may arise.
I truly hope this helps. There are 2-1/2 weeks left to write an acceptable offer before the April 30th $8,000/$6,500 Tax Credit goes bye-bye. If you need a good Realtor in Oregon, I'd appreciate speaking with you! Have a wonderful week! :-) ~~ Bobby