It looks like alphamale is assuming that James Spangler invented the vacuum cleaner in 1907. (If so, I'd have to agree that he was a janitor).
Unfortunately, there are those who would say that Hubert Booth beat him to it in 1901.
Then again, there are those who would scoff at the very idea of having to wait until 1901 for the invention of the vacuum cleaner. They would point to Ives McGaffey as having invented it back in 1869.
But don't mention any of this to the descendents of Daniel Hess. They'll point to his patent back in 1860!
So, before you and your colleagues argue about the occupation of the person who invented the vacuum cleaner, perhaps you ought to agree on who it is you're talking about!
(BTW: I don't know the occupations of Mssrs Booth, McGaffey & Hess!).
These two links will either resolve your arguments or stir them up! :
http://www.ideafinder.com/history/inventions/story042.ht m
http://inventors.about.com/library/inventors/blvacuum.ht m
Chris