In the early 90s a psychologist named Stanley Coren wrote a book called “The Intelligence of Dogs”, and it has been the standard for dog intelligence and capability since then.
The qualifiers for a “smart” dog are instinctive intelligence, adaptive intelligence, and working and obedience intelligence. It isn’t just about how much your dog can learn, or listen, but what they do with that.
It’s complicated to measure just how “smart” a person is, and they can communicate with others. Determining a dog’s intelligence is even more difficult!