Why are the floors stained or uneven?
The short answer
Handmade tiles are porous by nature.
Bejmat (handmade terracotta floor tiles) and zellige absorb moisture, oils, and pigment over time. Staining, discolouration, and surface wear are signs of age and material. Factory tiles wouldn't behave this way. Handmade tiles are individually fired and laid by hand, which is also why no two are perfectly level.