@Cirolle It affects NPC's as well.

Everyone will still be bloody with the mod. It only makes it more gradual in general combat. Stealth killing someone will still cover them in blood, and the bleeding debuff will still cover someone in blood. This mod doesn't adjust any of those.
With this mod if you take a hit that would normally apply blood, you'll only get 10-20% bloody instead of vanilla's 30-50%
Having said that, it doesn't take a high blood percentage for people to look drenched in it. At around 20% bloodiness it will already be a lot.
Nexus Mods has other versions of this mod that reduce blood further. I don't intend to upload them all here because there are a lot.

Thanks boss. The excessive blood was really the only thing that irritated me the most in the vanilla game.

Does it effect NPCs too?

Because EVERYONE is bloody all the time

lol Thank you. I just finished the game and I love how Hanush showed up at the end looking like he cut open one of the Paraguers and rolled around inside him!

That mod exists already I'm pretty sure, this one is for BLOOD only.

Can you make it so clothes don't get as dirty

Clothes get dirty because that's how the devs intended it. There's a mod called "Stay Clean for Longer" that lengthens the amount of time it takes for clothes to get dirty.

why do clothes get dirty after literally 10 secs

Nice!