I have to ask, how quickly does the sewers actively degrade a firearm that the cleanliness mechanic needs to be addressed?
To me as it stands it makes perfect sense. A firearm only gets dirty if you have it out of your inventory and in your hand. They don't get dirty from being safely secured in a holster. If this isn't so whoops my bad but I'm 95% on the holster part.
Which makes sense. If you actively have your firearm out in your hand and are expecting combat to happen at any second, you have sacrificed a hand in terms of stabilizing yourself as you wade through the muck. You are going to fall, and that firearm is going to go directly into the drink.
So if they remain perfectly clean until you actually skin iron, then the only thing that is degrading the cleanliness is the combat in the sewer environment. So how fast does a gun go from perfect cleanliness to a jammed piece of junk when fighting in the sewers? How long does one typically expect to be engaged in firefights in the sewers? Do engagements last so long that you can't get back to an arms tech to clean your weapon?
I notice that SMG's are being singled out as getting dirty really fast. Yeah, I think that's the point. From what I've seen of the SMG's on the market they are either designed as cheap UZI style knock offs or high end precision engineering like H&K. Neither of these design philosophies is conducive to extended engagements in literal shit. Fighting in the battle of sludge you may want an AK styled rifle for that, they can go through anything. I wonder if they exist within the game universe.
I do like the idea in terms of enhancing and firearms and we should explore these ideas, but in terms of sewers and keeping firearms clean, just clean it before you go down there, treat it like it's your genitals while down there, and clean it when you come back up. I'm sure your local arms tech will appreciate double the biz.