I have two dogs, both of them are Border Collie mixes.
Dog #1 is dumb as a rock. The first day we had him he walked over to my wife's purse and peed in it. I thought it was funny as hell and I liked this dog right away. But this dog is dumb and peeing in the purse should have been my first clue. He keeps making the same mistakes over and over and he is hard to train. He just doesn't listen very well and it's frustrating to try and figure out how to get the lessons accross to him. He's a fat lazy dog too. I have to watch how much I feed him because he'll eat anything you put in front of him. So, I've cut way back on his food to try to keep him at a healthy weight. What does the dog do? He stops moving and just lays around all day, so I have to feed him even less. If I feed him more, he just turns into a big pile of lard and can't move anyways.
Dog #2 is brilliant, seriously a smart dog. I had him house trained in two weeks, he learned to come and sit in three weeks, he learned the property borders really fast, and he won't jump up on you now even if you beg him. This dog plays and runs all day long. If the fat and lazy dog is in the shade trying not to work up an appetite, the smart dog will find a stick or a ball and play fetch with himself. He's constantly running around the propert chasing birds or kids or whatever. I feed this dog like a king, and when he's hungry he eats. If he's not hungry he'll save it for later. This dog is lean and muscular and the vet is always happy with the health of this dog.
Also, the stupid dog is always looking for attention. Always begging to come inside and scratching at the door (I hate that, have to refinish that sucker). If you open the door just a crack he'll push it open and run inside. The smart dog is the complete opposite, he's just as happy to be outside by himself. He actually has to be invited inside or he'll just stand at the open door. He likes to be petted, but he's never asked for it.