A few years back I saw a dog wander around a corner, across the pavement and onto a zebra crossing. Traffic stopped for it. The dog stopped. Only then did I realise that the dog was on the end of an extending lead and the owner was just around the corner having a good natter. Only when someone got out of a car and got the womans attention did she reel the dog in!
Those leads should only be used when the owner has passed a proficiency test! And a cycling one too!!!