I know that while many people get kind of nervous at the first sign of growling, face biting, humping and such, I think the general consensus among dog training professionals is that a certain amount of rough play is OK, depending on the dogs and the context.
Dogs with good social skills may get very vocal and wrestle, put their mouths around each other, and climb up on each other in a way that looks incredibly rough to us, and then disengage when they need to with everyone happy and unharmed.
Other dogs, like Star, will miss or ignore the social signals that other dogs use to keep things from escalating. For these dogs, us humans will have to intervene more often.
As I mentioned earlier, Star had some nice play sessions with Fozzie where they got loud and rowdy, and then got out if it on their own.
Speaking to the trainer at the shelter, I realized I don't have to. It was fun to watch them racing around the yard, but there are plenty of ways to get a dog adequate exercise without putting anyone in danger.
Fozzie enjoys running with a foster dog, but he always looks like he is a bit reluctant to do it, like he doesn't know quite how its going to turn out. I think I'm the one who needs to respect Fozzie's social signals, and protect him more from all these young upstarts I bring home.
Much as I enjoy a good play session, it is actually kind of a relief to know that I don't have to let them go wild. I can intervene before anyone gets annoyed, or in the case of a particularly annoying dog like Star, I can bypass that whole potential for stress by exercising everyone in a way that is best for him or her.
Do your dogs play like wild little beasties? How far do you let it go before you get nervous?