Excerpt from "Co-existing with Humans" from New Peoples in the Galaxy, 4355th Volume, third quarter: Cleaning Habits
Humans clean all the time. They clean themselves from head to toe every day, sometimes twice a day, and clean their mouths twice or three times a day, including dislodging material from between their teeth. They wash their hands after touching something that might have bacteria on it, after touching dirt or grime or oil, or even after handling something that they don't like the feeling of.
Additionally, humans will sterilize or wash their environments daily or weekly. They use bleach, soap, or other chemicals on surfaces that are used to prepare food daily or more frequently, even when the foodstuffs in question are already cooked and leave behind no visible debris. They will also sterilize bathrooms and showers even if no mold or growth is present and no harmful bacteria have been introduced. They soap and sterilize their floors less regularly, but are particular about not having any visible dirt or debris on their flooring, especially if they are not wearing clothing on their feet.
In addition to their desire for sterility, humans have a psychological need for the appearance of cleanliness as well. A dirty environment disrupts the human mind and makes them nervous. Clutter or disorganization, while acceptable, will not be tolerated in sterile or clean environments, and should be enclosed in boxes or shelves for humans' peace of mind.
However, some humans will not clean themselves of their environments, and will allow dirt and clutter to build up in their environment to the point where they cannot clean it up themselves, so they should not be left to solely self-regulate their cleaning behaviors. Multiple humans living together will regulate each other, but in the absence of other humans, other species must occasionally make sure humans are maintaining sufficiently clean environments for their mental and physical health.
This peculiar relationship and obsession with cleanliness makes small groups of humans ideal for living on interstellar vessels and traveling the galaxy. Family units and social groups generally range in number from two to twenty, and integrate well into diverse settings. These groups will self-regulate and clean for each other and often for other species around them. They are excellent workers for all manner of detailed work, and they are very good at identifying and dealing with pests, mold, or infections. Their cleaning habits and lack of secretions make them ideal scientists, doctors, explorers, and cooks.
Humans should not be employed with or live in environments with species that secrete mucus or slime, saliva, or other bodily fluids, or any species that leaves residue on floors, walls, ceilings, or other structures. Human reactions to environments and substances that they deem unclean can be violent or extreme, and they may do damage to themselves and others trying to remedy the situation.
