Of the six motive bars present in the Sims 4 (hunger, bladder, energy, fun, hygiene, and social) environment is absent. This is nothing new, as the environment bar was absent in the Sims 3 as well. In the Sims 3, the environment bar was replaced with moodlets. If your Sim was in an area with lots of decorations, they’d get a positive moodlet, and if they were in a pig sty with lots of dirty objects, they’d get a negative moodlet. The Sims 4 incorporates environment-as-moodlets in a similar manner, but gives the whole system some major enhancements along the way.
Let’s start with the negative side of things. Just like in all versions of the game, objects get dirty; food on plates goes bad and puddles can form from accidents (both mechanical and biological). Having one or two of these messy objects in a room did not alter the mood of my sims, but once enough of them piled up, a +1 uncomfortable moodlet popped up for a dirty environment. Let the environment get more dirty and the moodlet grows in strength. While I did not test this directly, I would imagine slob Sims have a greater tolerance to (or immunity to) filth, while neat Sims would get bigger penalties than normal.