It’s not ammonia that deters them, it’s the urine of their predators. Wolves and coyotes are their predators. Canines like dogs hunt feline creatures like cats and raccoons. Humans cannot eat them as our bodies have gotten used to cooked food over the past seventy thousand years. We cannot eat any meat that is raw, even beef which is very safe to eat raw can still make you feel sick. This is why creatures like vultures, wild cats and raccoons are considered carry-on feeders. They will wait for a stronger bigger predator to kill something and then wait for it to leave and eat what’s left. Vultures simply fly over you until you die from the desert heat. Either way, carry-on feeders make up a very important part of our ecology. They eat things that are a biohazard to us and then defecate that material out which helps plant life grow. The only issue is with raccoons defecating on your property due to the presence of one of the most dangerous parasites in the world: Baylisascaris procyonis, a roundworm nematode, found exclusively in raccoons. AKA: Raccoon roundworm. This parasite is incurable and deadly. It can infest you by eating just one egg which is a serious danger for children and pets. That being said, when it dries it becomes airborne and can infect you through the lungs, eyes and mouth. This is a severe biohazard and needs to be cleaned by a professional with hospital-grade botanical sterilizers and boiling steam over one hundred degrees celsius. There is no way to cure the infection which will grow at a rapid pace. Anyone with it can continue living their life but the symptoms will increase and living a full and complete life will be impossible. Without constant medical aid, the person will die rapidly.
If you are finding raccoons wandering your property skip out on the urine sprays and the critter ridders. These animals are not here to hurt you, they just want some food and water and a place to stay for the night. Sadly you cannot let them in. You need to keep them off your property by removing and barring any access to food, water or shelter on your property, lest they try to make a den in your attic space. If this is the case do not try to get it out yourself. Call a skilled and trained and preferably insured technician to humanely evict the raccoon and then seal off the area from any other animals that may want to get in.