I've been enjoying decorating my sims' rooms more to fit their personalities and it's fun to add messes around the rooms of really sloppy sims, but right now all I have is that one vanilla dirty clothes rug and I was wondering if anyone knows of more CC that's similar to this. Doesn't need to be just clothes, any kind of messy clutter would be nice to know about.

Well, I focused on finding clothes clutter because I didn't see the "any kind of messy clutter would be nice" until just now. But honestly, if you get specific in your searches--like toy clutter, music clutter, etc. You shouldn't have trouble finding stuff. A lot of 3t2 and 4t2 sets are great for clutter items.

But anyway, clothes clutter. I tried to focus on find you items that specifically were on the floor, giving off a messy-sim vibe. It was a pita to search because I know exactly what you mean but the search results weren't great, especially since some of these are old. So first, the newer stuff:
VKG & SB Bioshock Infinite Luggage as dressers by Influence. It looks messy and it's functional!
Life is Strange conversions by 2FingersWhiskey
AroundtheSims Squat Bedroom Clothes Pile; also available as a dresser by CreeSims

For older stuff, I'd recommend checking out Simply Styling; it's archived here: https://archive.liquidsims.com/mirr.../homesims2.html
(Make sure you have an adblocker before you visit; I always get a redirect attempt when I first visit there and close the pop up box.)
Specifically check out deco sets 14, 15, 17, and 19
https://archive.liquidsims.com/mirr...cosims2_14.html
https://archive.liquidsims.com/mirr...cosims2_15.html
https://archive.liquidsims.com/mirr...cosims2_17.html
https://archive.liquidsims.com/mirr...cosims2_19.html

Then Riekus13 often has recolors of those older clothing pile deco/clutter; here's a few links, but you might want to check out the whole tumblr:
https://riekus13.tumblr.com/post/17...eater-converted
https://riekus13.tumblr.com/post/16...-poccis-eclipse
https://riekus13.tumblr.com/post/14...e-entire-family

And you might also want to check out Cassandre's Color Trends Fashion Boutique and The Closet sets. More for shops, but lots of good clothes clutter in there. (Linking to the Pinterest Pins so that you can preview before you download):
https://www.pinterest.es/pin/571886852689339848/
https://www.pinterest.nz/pin/571886852689339883/

And for shoes there's plenty out there but The Ultimate Collection Clutter Collection: Shoe Edition by Shastakiss should have you covered and there's another mini collection of newer shoes by MDP here. And that's all I'm going to link to because honestly, plenty of shoe clutter out there to find.

Finally, some tips for clutter, in case you don't know: you might want to make sure it's quarter tile enabled so that you can place items closer together and off the grid, etc. Sometimes with older cc it's not enabled so to do that, open up the item in SimPE. Go to the OBJD line (Object Data). If you're in Plugin View (Check bottom of SimPE), you should see two tabs, Catalog Sort and Raw Data. Catalog sort is where you recatagorize, and Raw Data is where you change the price, among other things. Click on Raw Data, then select "Decimal" and then find line 0x0022, "Sale Price". Make sure that says 35 (again, in decimal, not hex). Select "Commit" and then save, and you should be good.

If you find you can't place the clutter you want on the surface you want (a shelf, end table, the floor, etc.), you can change that too; check out Changing the object Placement by Numenor.

Thank you so much, this kind of stuff is exactly what I was looking for. I spent a while yesterday searching google for those kinds of things but I didn't find anything at all, it's kinda crazy.. So this is so helpful, thank you!!