All pet experts have different opinions about what a good dog is. Here is my opinion as a groomer.
To simply say, a good dog is one that you can pleasantly live with is not enough. I would add something else.
A dog with whom you and also other people are pleased to interact.
If you have friends who know your dog well and volunteer to take care of your dog while you are away, I would say ” That’s a good dog.”
A dog that anyone would like to adopt or a dog that gets adopted easily without a problem.
These dogs have certain characteristics and are liked by everyone. All of this makes them good dogs in everybody’s eyes.
I would list the four traits all ” good dogs” should have.
1) a dog that is housebroken.
2) A dog that is well sociable both with adults and children.
3) A dog that you can handle and allows you to touch any part of its body and also accepts grooming. This means you can keep him/her clean and neat.
4) A dog that is healthy and attractive and hard to resist to hug or pat.
You can find information about housebreaking, socializing, and pet health in general on other websites. I will focus my grooming tips mainly on #3 and #4.