The key thing is, it's effective and not exorbitantly priced.
Out! Petcare's Stain and Odour Remover really does the job, we have a young rabbit that we are trying to litter train, and whenever he has no morean accident, out comes the Out! It's easy to use and pleasantly fragranced, so no more nasty smells or stains! It is a natural pro-bacteria and enzyme solution so no nasty chemicals, it also gets rid of the pheromones that cause an animal to re-visit the 'scene of the crime' and have a second go. It claims to get rid of such stains as "blood, vomit, faeces, urine, pheromones, dirt,grass, coffee and more", I can only speak for rabbit urine and faeces stains myself, but that's what it says on the bottle. You can also use it on or in your laundry or in carpet cleaning machines and it's recommended for all water safe surfaces - DO NOT use on wool or leather.