Cleanliness and brain circuits I have noticed as I am sure almost everyone has, that being a dirty cluttered environment makes one feel bad, and being in a clean environment can make a huge impact on how you feelIts indicated by the words we use to describe a cluttered environment like "disgusting" "nasty" ect. And from personal expirience, I have noticed that simply looking at an something like a dirty bathroom or countertop can make me feel disgust. It also makes perfect sense from an evolutionary psychology prespective because if one was in a dirty environment, they would be more likely to die from disease obviously. And clearly the drive to have a clean environment is quite powerful, since things tend towards messiness quite quickly, so it requires constant effort to keep a clean environment, yet most people manage to put in that effort nonetheless or pay people to do it. I don't think I need to belabor this point any further, clearly there is a strong need for a clean environment.