Hi, nr. I will try to answer your question. Then we'll hopefully see what others have to say.
First of all, a dog has to have natural instinct. Blue Heelers, heel. Border Collies work cattle differently than heelers. Aussies tend to heel. Catahoulas are HEAD dogs. You must understand how the natural instinct works in a dog. Some people cross Border Collies and Australian Shepherds, but as a breed they work differently. Not saying the cross isn't good, understand. I think it is extremely difficult to teach a dog to heel that is not a natural heeler. Blue Heelers don't want to work very far from you. Border Collies and Aussies will go where you send them. They will go after cattle quite aways away. I think good dogs check back with you to see if they are to continue on or return. Seems like every good dog we have had has this common characteristic.
It is said that Border Collies are the smartest of all dogs. We have found, for us, Border Collies are a bit too hyper and probably too smart. They really like to have something to do most all the time, or they will find something to keep busy. Border Collies make excellent trial dogs and obstacle course dogs. I feel there are perhaps two types of Border Collies. Trial dogs and ranch dogs. I could be wrong, though.
Personally, we like dogs that heel. Maybe it is because we are more familiar with how they tend to work. Our big dog, Aussie and Blue Heeler cross, is very quiet and mellow. He will work up the side of cattle when moving them to keep them together--he goes back and forth making sure he gets them all. Our old yellow dog was a heeler, but if a cow wanted to make a pass at her and not go where whe was supposed to be headed, the dog stood her ground and turned the cow around. This dog tended to stay after that one cow a little more than she should. But she was tough and smart. She saved my husband many, many steps. Like someone posted earlier, when you are by yourself, a dog can make working cattle a whole lot easier.
After instinct, comes minding. If a dog doesn't mind, he is merely a pet and a poor one at that. My husband instills minding very early and he never has a problem with his dogs. We can be riding along and the dogs range further out than he likes and he can say to me, very softly, "those dogs better get back here." BAM, thier butt goes in the dirt, they turn and come right back and get in behind the horses. (This isn't when cattle are present, but going or coming from a job.) No one has raised their voice, they are just listening~"tuned in", if you will.
My husband doesn't pretend to be a dog trainer. He loves 'em, he spends time with them, they understand what he wants and they mind. Some people can teach dogs a lot more than he can, but he is satisfied with how they work for him. It takes time and patience and he gives it early on so it is never an issue later. He never uses violence or pain to train a dog. NEVER.
When we lived on a creek, my husband could tell the dogs, "See Birds?" They would run to a tree and look up in the tree. He could say, "See Fish" and they would run to the creek and look in it. One dog (part Catahoula) even jumped in and caught a fish!! (TRUE STORY!!) He could say, "See Rats" and they would run to a wood pile and not only look for rats (we had pack rats in that country), they would proceed to move the boards with thier mouths to find the 'rats.' It was so funny and illustrates how much the dogs understood. As you can see, my husband uses his dogs for help, companionship and entertainment.
Another place we lived, the barn had a haymow. The cats stayed in the barn. We had three blue heelers or blue heeler crosses. As a breed, they hate cats. They devised a plan in that two dogs would go up in the haymow and run the cats down. One dog would set at the bottom of the stairs to get the cats that ran down. Good idea, but it never worked. The cats would go part ways down the stairs then jump over to a shelf under a window and then get away. The dog waiting at the foot of the stairs never figured out to go partways up to intercept the cat. Of course, we wouldn't let them kill a cat if we could help it. This was so funny to watch, we let them have their fun. The cats always won anyway.
So the answer would be a combination of things. You do need to have a dog that is bred to work. However, as in anything, that is not always true. Dogs can always suprise you. Another thing we have learned is that it takes some dogs longer to mature than others. Pete, our older dog, was over a year old before he showed any inclination to work. I had given up on him. Then one day he just started paying attention. (I think it had to do with him being a male~). Dixie, on the other hand, is already wanting to do things. We don't want her to get hurt, so she has to stay back, but she is SO interested at only four months of age.
Hopefully, this shed a little light on it for you. I will be interested in what others have to say.
Jinglebob, loved your poem. Did you just come up with that off the top of your head? AMAZING!! And there probably are instances where the dog is better than his owner. (Ouch!!!) LOL!!!!