I'm always amazed when an artist confesses to being afraid of drawing feet or hands. It seems that because we use these appendages so unconsciously that drawing them, for some people, is nearly impossible. I never had that problem, but I was never very interested either.
Feet often fall outside the frame. HR advisors often suggest that you consider the condition of someone's shoes before hiring them. Shoes do take on a variety of shapes from different angles, so depicting them accurately can be a challenge. Thankfully I don't have a lot of shoe practice pages in my sketchbooks.