I agree.
It may be more humane to allow a shelter to euthanize a dog like that, than it is to leave it in the hands of an inexperienced owner.
Most dogs have very reliable and easy to read body language, but I can think of at least one exception.
I was about 10 years old, visiting some friends. We were outside playing. Their home was pretty far back in the woods, so they habitually allowed their dog off a leash.
Medium/large sized mutt, no idea what was in his genetic makeup, but he was fluffy.
He seemed quite friendly too, I had been there for a few hours and had pet him several times.
I still don't know what the trigger was (personal space? location?), but the last time I reached over to give him a pat he
freaked out, lunging and snapping at my face.
I managed to throw my arms up over my face, and dodge out of the animals immediate reach..
The parents of the kid I was hanging out were thankfully right there and saw what happened. They grabbed the animal quickly and made a big fuss over me. They must have known the dog had aggression issues.
Two years later, I was informed that the same dog had been put down, after biting a child's ear completely off.
I still wonder why the dog's owner hadn't taken measures to prevent it when they clearly knew he had issues!!! :evil: