I think it depends on the dog and it depends on the owner. If both are well trained I think dogs are fine. I little bit of common sense goes a long way. I actually stop and thank people who make a point to separate their dog from me or pull off the trail when we pass by each other. On the other hand I constantly see people walking their dog off lead and when I tell them that is actually against the law their only reply is "Don't worry he's obedience trained."

So I would say if the dog is going to be on a leash, not barking incessantly, not invading anyones space and not bringing any harm to the wilderness, why not bring it along.

As long as I have been hiking and backpacking I have never known a dog to leave a beer can or a cigarette butt on the trail. I also haven't seen them throw garbage all over a pristine beach or carve their name into a tree or write grafitti on a rock.