The phrase "janitor for" is correct and usable in written English
It can be used when describing someone's job or occupation as a janitor. Example: John works as a janitor for the local school district. He is responsible for keeping the classrooms and hallways clean and tidy.
His father was a janitor for the local office of the federal Bureau of Indian Affairs.
Mr. Mixson, who works nights as a janitor for Merck, the pharmaceutical company in Rahway, N.J., said he was outraged.
Every minister in the new government makes the same as a teacher — or a janitor, for that matter.
He lied that he was told to come back, and bluffed himself into a job assisting the janitor, for three dollars a week.
Juxtaposing white-collar callousness with brown-collar invisibility, Mr. Russo — who worked as a janitor for 11 years — picks at society's pecking order with inventive zeal.
Boy George had offered to donate the proceeds of one of his concerts to the city instead of playing janitor for a day.
They were janitors, for God's sake.
But the hog farmers fear the capital of the corporations, & fear that they will be forced to serve as mere "janitors" for livestock.
(Romney's a looter! Poor kids should work as janitors!) For this, if he wins the election, Romney owes him an ambassadorship, at the very least.
In October, federal agents raided 60 Wal-Mart stores in 21 states to round up more than 250 illegal immigrants who were janitors for contractors for the retailer.
The S.E.I.U., with more than two million members, has probably done the best job among large unions of adapting to the new workplace, organizing health-care workers and janitors, for instance, in circumstances that did not allow for traditional industrial organizing.
