Granted, I wouldn't ever physically correct someone's dog, but you can bet I'd be very pointedly telling your dog to get off and expecting you to step in and remove him (which it sounds like you easily can and would). Some people are fine with humping; I happen to not be one of them.
I guess my rule would be "watch your dog and his reactions, and watch how other dogs and people are reacting to your dog; manage accordingly."
I do tell him to get off when ever he's humping!!! The thing about Fozzie is, he doesn't "grab on" to the other dog like he's sexing them. He just kind of puts a paw up on them, freezes then zooms around. And the other dog was doing the EXACT same thing as him, putting paws on his back then frolicking around with him. It wasn't a rape scene in any way. And the other dog's owner straight up kicked him in the chest.
Our dogs were really having fun playing, but after that I didn't let him anywhere near that dog. If Fozzie was bullying that dog and forcing himself on him, I wouldn't be so offended.
I feel that all dogs play mimicks real life behaviors: hunting, stalking, chasing, killing, and mating. Just because dogs are wrestling, that doesn't mean they are going to kill each other. Just because dogs are playfully humping, doesn't mean they are having sex with each other. I do agree with your last sentiment though. After working in dog daycare for years I can instantly spot when dogs are uncomfortable or tension is rising, even with other people's dogs, and I'm quick to body block or distract them to break it up. But I don't feel it is EVER ok to physically harm another dog unless there is a fight or there is certainly about to be a fight. I wouldn't even physically touch dogs when I broke up fights in dog daycare, except to grab their back legs, and I NEVER had fights even with 20 huge dogs in a small room.
1 If you have food. Especially strong smelling food my dog is going to stare at you. She will watch every bite so intense you may become uncomfortable. She won't take it but if you don't want a dog to watch you don't eat there.
Seriously!!! This lady came into the dp the other dog with a bag of Del Taco... and literally a dozen dogs were mobbing her, jumping all over her, and snapping at each other. Why would you want to eat tacos in a dirty, germy dog park anyway? She was like, "Oh! I probably shouldn't eat in here!" and we just nodded. It's on the sign in the front, actually. A dog could nab one of those delicious taco wrappers, eat it and get a blockage. Who is to blame?