And when someone looks at you and says "uh...." with that look on their face, or even walks in gripping the lead like that dog is going to eat someone, you'll know. Dog expertise NOT required.
Can you always account for every single thing the dog may encounter? No, that's not possible. But you can certainly weed out vicious and unstable dogs of all ages and if I were running a park, I would want to meet guests' dogs long before other guests had a chance to.
If I were a CG owner I would NEVER take on the liability of deciding which dog is safe to enter a CG and which is not. That's just plain ludicrous.
Hypothetically, If your park becomes advertised that the "owner" will decide if your dog is safe to enter this park? Open up your pocket book to lawsuit after lawsuit when the "deemed safe by you dog" bites a kid or gets into a dog fight".
I can bring you a dog that has so much obedience in him you'd think he was a saint, the perfectly trained cute safe dog, and at the drop of hat or gnat that flew by he'd take your face off in a nano second if I allowed him too.
AND......THE most common dog bites come from FEAR BITERS. You know the shy, unsuspecting quiet dog? :W