Plumber vs sales

Plumber vs sales!  What could be more beneficial for a company? How could it be better for the company reward their employees, hourly or commission? When the employee will be more interested in doing a better job? Is the company loosing money paying the employee hourly? When? And if why? Doing the job should the plumber give information about the work the owner? Is he sure his idea is the same with the sales person? Will he not damage the relation with customer? Questions. Questions.