If your are comfortable with washing your dog in the shower then it is fine, at least you can save money by skipping the pet store and you can have bonding time with your buddy. The advantage of going to the pet store is that it is more convenient for you not dealing with your wet dog at home. In our household, we wash our dogs in the backyard by using a hose and we do not mind getting wet since we are outside and it is also a way for us to bond with our pets. We never wash them inside the house or the shower because it would be really messy and parts of the house would get wet since the dogs are very active and always running around. There are seldom times that we go to the pet store but we always want to save money and shelling out some cash just to wash the dogs is really costly for us, so we would rather just do it ourselves at home.