Plumber is a category as well. The difference is that plumbers do not gather once a year to declare the Eternal Principles of Pipe. There is no Council of the Wrench. No one is arguing about the True Spirit of the Elbow Joint. They simply tighten the fitting and go home.

I believe Adam Savage has relayed the Plumber's Manifesto at some point: 1 Shit flows downhill 2 Payday's on Friday