My Kenneth Cole Reaction tri-fold is getting pretty grungy. New credit cards and business cards are getting gunked up pretty quickly.
I tried googling it, but my google-fu must not be up to snuff.
Someone recommended using saddle soap to clean it.
Do most people just buy new wallets?
Scrub any lining (assuming it is cotton or nylon) with a little dish soap and a hard brush (like a dish brush)
Clean any leather parts with a damp (not wet) sponge and a little saddle soap. Dr. Bronner’s Castile Soap and Murphy’s Oil Soap work in a pinch if saddle soap is not something you own.
If you want to go really crazy, you can condition and waterproof the leather with minute dabs of Mink Oil.
Shoepolish?
You buy a new wallet normaly. Grime works into the leather. I do buy new plastic card holders though.
A man will by a new wallet more often than underwear. 
I think you might be right. Just did a check for a cheapo tri-fold, and I can get one for around $14 online.
I’ll probably spend half that on the saddle soap.
Of course it’s not Kenneth Cole, but then why do I need an expensive wallet. Seeing as it’s going to spend most of the time, in close proximity to my ass.
Thank you for the responses.
My old wallets go into the records drawer with all my expired ids and cards. It starts you out with a thin wallet.
I switched to cheap nylon wallets years ago for that very reason. Leather just gets grimy and is hard to clean. Nylon is cheap…toss it when it gets worn and buy another. I think I paid $15 for three of them last time at a swap meet.