If i were to be charitable, many of the ones that do this are the people that are just getting on the trail as I am coming off of it. Their dogs are running well ahead of them, and the owners are beet red and and having trouble with the trail. The best I can say is they aren't aware of what their dogs are doing when they're out of sight because they are more well behaved when the owner is there.

At worst, I think they just don't care.