Dirtiness easy mode: after 2 days of not washing just enable “dirty” regime which very slowly drain hidden health parameter and increase chances to get infected/start vomiting.
Dirtiness mode: each item, including each part of the body, gets dirty parameter. You can make items dirty by putting them in pools of blood and dirty toilet/sewage water, wearing them, vomiting at them, getting splattered in blood or plant juice from killing enemies; make them cleaner by washing them or using things made of cloth and paper like towels to split dirt in half (if you had left hand with 6 dirtiness and clean towel - you get left hand with 3 dirtiness and towel with 3 dirtiness). High dirty values make weapons fail, fail cooking crafts, make bandages and first aid useless, produce smell (making it possible to trick ants and other smell reliant mobs by throwing items you have just vomited at far away so that they will pursue their smell and not yours); eating with dirty hands decreases health and may make you vomit. Liquids and wet things (if they will ever exist) can take all the dirt on themselves. There will be finally real application for bleach apart from crafting, also soapmaking would be neat.
Items have maximum dirtiness, for example rag can have only 1 dirtiness max while towel 5 and raincoat 50, 0.25l water 10 and so on.
Also there will be no need in having things like ‘water’ and ‘clean water’, it will be just water with some dirtiness, there will be no need to waste charcoal in charcoal purifiers, instead charcoal just gets dirtier (and it can then be burned).
Dirtiness on non-liquids can be seen easily while in liquids only approximately (0-5 transparent water, 6-8 muddy water, 9-10 opaque water or so), to measure it accurately you’d need a chemistry set and 0.25l of said water.
