I know Julie has some extremely less than ladylike poops! Whew!!!!!! She also doesn't always get them covered well when they are particularly bad. She eats the same thing all the time, no wet food, no people food, not even any kitty treats...she won't touch anything but her dry food and her cat grass. I don't know what causes the smell to change greatly from one day to the next. I have noticed though, that when I have fresh cat grass for her to eat the poops are a lot more bearable.