Since the shoe is the dwelling-place of the foot, the lowest and dirtiest part of the body, which is in constant contact with all sorts of dirt, it is not difficult to understand why in some cultures showing the bottom of these ignoble objects is a mighty insult.

Keep your soles hidden by sitting on them if you are asked to sit cross-legged on the floor or by tucking them underneath you.

Revealing the soles of the shoes is an insult in all predominantly Muslim countries.

It is worth noting that, before entering a mosque, one removes one's shoes as a way of maintaining the purity of the place of worship - though whether this is the cause or effect of the sole of the shoe being considered impure is not clear.