Yes, you should always take your dog to an experienced groomer who can form a bond and calm them down before grooming. Dogs with a problematic past have difficulty trying new things and might be traumatized at groomers. Other than that, dogs who are not used to grooming sessions or are not in the presence of unknown human beings will have trouble understanding why an unknown human is touching and probing them in places not even its owner does. Also, there can be accidents at a groomer's location that can cause your dog trauma.