There are some jobs that Americans just won't do anymore, some say, which is why we need illegal immigrants to do them. You can't say that of Mike Rowe, host of Dirty Jobs (Tuesdays, 9:00 p.m., Discovery Channel).

"I explore the country looking for people who are not afraid to get dirty," he says in the show's opening. "Hard-working men and women who earn an honest living doing the kind of jobs that make civilized life possible for the rest of us."

The wise-cracking host apprentices himself to roach exterminators, hot tar roofers, livestock artificial inseminators, and disaster cleanup crews. He picks up road kill, shucks oysters, services septic tanks, and swings a sledgehammer.

In the course of the show, viewers come to appreciate the skills and gumption of people who do this for a living. A rough, grubby-looking potato farmer from Colorado turns out to have the chops of a research biologist, cloning plants and engineering new kinds of potatoes. We learn about the complexities of feed mills and turkey farms, what farmers do with manure, and how impressive sheer manual labor can be.

When Mr. Rowe is tasked with replacing a pump for raw sewage in a waste treatment facility, a hard-hatted technician blithely ticks off the dangers in this line of work: "engulfment, drowning, hazardous atmosphere, slips and falls." As they crawl through pipes and wade through nauseating sewage, twice they have to leave fast when poisonous gases build up. But they finally get the job done.

The show is rated TV-14. Mr. Rowe sometimes blurts out a profanity when he is startled, and the show is often, by its very nature, gross.

But Dirty Jobs is a tribute to the dignity of labor-even when that labor deals with undignified messes. As such, it testifies to the Christian doctrine of vocation, according to which human beings serve God by serving their neighbors in the ordinary tasks of everyday life.