Alot of people that really dont know dogs, dont understand how important this type of playing is.
My Shep loves to play....it doesnt take her very long to get aggetated (sp) and starts to play rough. I flank her and she will get stupid quick. I peak her nerves and then shut her down. I control her mentally and have to or she wouldnt be managable. You have to be the leader, or they will think they can take over and lead. With any large breed dog, once you have let the dog get the upper hand mentally, you have lost control and then bad thing start to happen, even if its minor as them soiling in the house.