Working on that. Still would prefer cats to skip my garden though!

Hahah simply. I've only trained a handful of dogs, so professional dog trainers sound off here but there are dogs that are more or less untrainable. Sure difficult dogs can learn a few manors or tricks, but either because an abundance or lack of intelligence they're not going to ever be a show dog. Depending on the dog maybe the best they get is just not as reactive instead.