What should poo look like?

The seven types of stool are:

• Type 1: Separate hard lumps, like nuts (hard to pass)
• Type 2: Sausage-shaped, but lumpy
• Type 3: Like a sausage but with cracks on its surface
• Type 4: Like a sausage or snake, smooth and soft
• Type 5: Soft blobs with clear cut edges (passed easily)
• Type 6: Fluffy pieces with ragged edges, a mushy stool
• Type 7: Watery, no solid pieces (entirely liquid)

Types 1 and 2 indicate constipation, with 3 and 4 being the "ideal stools" especially the latter, as they are the easiest to pass. 5-7 being further tending towards diarrhea or cholera.

Source: Wikipedia