Chicken poop – comes in quite a range of normal inappearance – huge range.
Observation – as in: look at your chicken’s droppings frequently is a cornerstone to be able to notice finer details when something is “off” later on. There is no substitute for that experience.
One concern is always: blood. So it is good to know that chickens periodically shed some of their intestinal lining – and that can show up as red in the chicken poop – no reason for concern.
Mustard to dark brown frothy poops are expelled about every 8 to 10 droppings. These are produced in the caecum of the chicken and are called caecal poops.
Here is a great page with various normal and abnormal chicken poops – the smelliest I have encountered is that of a broody hen 🙂