I think my friends on this forum have said everything? Ventilation is key, as it takes away the ammonia from the droppings. My birds are free-range, and the coop is open all day so I don't have this problem. Normal droppings are no problem. When a chicken eats something it shouldn't then it can result in slimy droppings. I clean these off with a knife from the perch and bin them, as they can contain infection. Some chickens fart, just like we do, so you can get a smell that is temporary. However, anybody who keeps animals learns that smells come with animals, and that applies to horses, pigs, sheep and chickens. If you want your chickens to smell like jasmine, then I would suggest you are puffing stuff into the coop that they have to breathe. It might not be good.