Dogs are a very big responsibility. If you change your mind after you get your dog, or your family decides it wasn't a good idea after all, then it is the dog who suffers. We know as many end up at our shelter.
Some dogs bark a lot.
When you walk a dog, you have to pick up the mess. Dogs can get sick and mess up the carpet. Dogs can chew furniture. Some dogs shed hair. Dogs get lonely when they are by themselves.