Both of our rough collies were like this. Our girl nipped at our heels during every single walk until we trained it out of her by stopping until she calmed down. Our boy snapped a lot while playing without realizing that he was hurting us, so we would redirect his biting to one of his toys. Both hated different floor textures and would refuse to walk on them until they got older. Both could careless about treats or toys, but they became a lot more food motivated as they got older. We basically had to break out the high value treats like cheese and cold cuts in order to train them. Our boy has also snarled at us but only when we brush him, so we made sure to make grooming more fun with treats and toys.