Professionals do all the work. The worst part of dog shows is the part that the spectator never sees. Loading and unloading the vehicle, lugging crates, grooming tables, and grooming equipment into and out of show sites, pottying dogs, cleaning up after dogs, exercising and conditioning dogs, feeding, watering, and medicating dogs, grooming dogs, and transporting dogs all take place before the dog and the handler step into the ring. You are paying for much more than the handler's ring expertise. Your desire and ability to perform all these tasks should be considered when you make the decision to hire a handler instead of doing it yourself.
Professionals often do a better job.
They may not show your dog the same way you would, but a professional's reputation is on the line every time that he steps into the ring. If you select a handler with a lot of experience in your breed, you should get superior conditioning, grooming, and ring presentation. Not because you are paying for it, but because the handler has years of experience performing those tasks on hundreds of individual dogs in your breed. Professionals are at a lot more shows. The ability to travel every weekend is often critical to finishing a dog.