Bagredo1

Hi, When I use cleaner on leather that's really gross, as soon as it's wet with cleaner the dirt marks appear. It doesn't really come off at all. I can scratch off the top scum with a fingernail but should I have to? I have tried a few leather cleaners, Bick, Apple, Weiman and now, Leather Ultra Clean by The Furniture Clinic. Please help, you guys know so much!