I have two cats and recently took in a stray cat for a month. I think the stray cat had marked a few spots which fortunately were mostly on/in items and not directly on the carpet. However, I wanted to clean my carpets just in case to get any lingering smell out. This cleaner has a very pleasant smell - not overpowering, just the smell of clean. When I dumped the dirty water, it was a dark brown, almost black liquid. I had no idea my carpet was that dirty since I just had it professionally cleaned a year ago and I don't wear shoes in the house.