I have had excellent results with Bick leather cleaner and conditioner. I was always too cautious about cleaning leather and never really realized how durable it is. It can take a pretty aggressive cleaning if necessary. I bought an expensive (if new) leather chair that was trashed for a couple of bucks.
It was mostly filthy from use and neglect but it also had a small tear in it. Using Bick cleaner and a stiff horse hair brush, I was able to scrub out all of the dirt and stains. I worked in small areas and wiped off the dirty solution with clean towels. Literally wash, wipe, repeat up to 3-4 times per panel until the towels were clean. It was sort of like cleaning a barrel until getting a clean patch.
I found a local leather repair guy that patched up the tear and color matched the dye. Once I got it all back together, it looked brand new. I can’t say enough about Bick products. Well worth the money.