I’ve noticed that janitors are traded in Jita as if they were slaves. As slavery is prohibited in Caldari State, this should mean something different. Here is an explanation I came up with in my in-character blog post Who Needs a Janitor?
A sell contract for a janitor means a sale of a contract option. A person can sell his commitment to sign a contract for cleaning services on the predefined terms except for the location which is determined solely by the option owner. For the seller it gives a chance to increase his income or, at least, get an advance payment even before the contract has started. For a buyer it means guaranteed workforce at a location of her choosing and fixed cost. At times, like after destruction of Fort Knocks Keepstar in Rage when contract rates in Anoikis are sky-high, exercising such option may even reduce the HR spend.
I wonder if there is another explanation of janitor trade on Caldari markets.