I bought a pair of seal skins for the Kirby Stephen Yomp when very wet weather was forecasted. My feet were wet by the time I got to WildBoar Fell. I considered testing them again at home before taking them back to the shop. Sat with my seal skinned feet in a bowl of water for an hour (made sure the neighbours were'nt looking!) and they were perfectly dry afterwards. So the leaking seems to be something to do with the movement of the sock. Still, as others have mentioned as they do keep your feet warm for cold winter runs I've hung on to them. However it's a case of definitely not doing what it says on the 'tin'.