I learned this when in Australia. I do massive amounts of walking, covering alot of ground when sightseeing. My feet would start to become really sore after a few days into my vacation. I followed this tip...after coming back to my room from a day of sight-seeing, before going to bed, shower or wash feet, rub vicks vaporub on feet and then put on socks so the bedsheets won't stick. The next morning, not only will your feet be clean but also feel great and you can go through another day of walking.
Just wanted to share this as this really helped me get thru on my last vacation for 3 weeks.