Soo, here's an update. I have given up on any options using paint, I just don't trust it. I ran into a friend and he gave me an idea, he recommended using bleach, to be more precise, something with chlorine.
We call it Chlorix, it is a cleaning agent, also used for bleaching colors and such. So i got a bottle, diluted it 1+1 with water and used cotton swabs. It got at least a bit better but the human fat and such seems to have seeped into the fabric and plastic and the discoloration seems to be permanent.
Anyway, I put it back on the camera and it looks at least ok. I have a different problem now, the lever under the front plate pushing up the release button does not move freely, the button does not come up completely and so, sometimes, the shutter opens when cocking. I've had a similar problem before where I had diassembled almost the whole camera because a screw of the mirror box had fallen in a corner of the camera and would not be shaken out. Then the button would not come up and I had to disassemble the bitch again just to find out what was wrong. Then the leather thing and now the button again.
I'm sick of it. Maybe in a week or two.