A properly trained operator using the right equipment for your vehicle type should not cause any damage. Damage typically occurs when the wrong towing method is used (improper towing of an AWD, for example), when attachment points are incorrect, or when the vehicle is not loaded correctly.
Before the tow, walk around the vehicle with the driver and document any existing damage with photos on your phone. If damage occurs during towing, report it to the company immediately — reputable towing companies carry liability insurance for exactly this reason.