I bought those used and they looked kinda beaten and blotchy. Revived with some no-name leather grease and darkened them considerably. For the next year I beat them to hell and back a couple times and treated with SnoSeal. At that point they had a nice layer of gunk and grease on them and looked like they were black.
Got tired of the lifeless dark leather and scraped most of the shit off with a dry rag and some cleaner/conditioner, might have been woly or some other Finnish bramd. They lightened considerably and I was happy for a while.
Last august I decided to wash them dish soap inspired by this video. Instead of Obenauf's I treated them with a light coat of Saphir Renovateur. For the first time they looked clean. The dish soap got almost all the crap off the leather but left the leather really dry. The Saphir revived the leather and left it nice and light. I had gotten used to sheen on cap toe so I brought out the old no-name grease and that with damp rag brought a nice contrast and sheen. Since that they've been my go to boots for when I go see some live bands. They've gone through litres of beer and imagineable shit during punk/metal shows but that has cleaned off quite well.
I do not recommend any of that haha. Ok, maybe the Saphir Renovateur.