thank you all for quick responses.... well previous owner never washed the car i guess, i sprayed leather cleaner/condition and with one pass, towel became grey(white terry towel). there is no special stains(juice, blood, oil, etc...) just from never washing/cleaning it. also need tips on carpets too, not the floor mats but actual carpet. it needs mad cleaning.
The thing to keep in mind when cleaning the leather is that you are not cleaning the leather. You are cleaning a coat of paint. The leather is underneath the opaque urethance coating. What you are looking at is paint. The dirt or stains you see are on, or in, the paint. This is a thin coat of urethane so using anything abrasive may well rub the coating off and the split leather hides underneath can look damn ugly.
I proscribe to the Leather Masters product line and use them on all my personal vehicles. Their products work very well. Be sure, no matter what cleaner you use, to be **** about removing all traces of the detergent after cleaning. Wipe down the seats with a clean damp MF and let them dry for several minutes. I'd suggest that an important and often overlooked product to apply is a leather protectant. Many will use a conditioner and leave it go at that but its the protectant that will make future dirt and stains easier to remove.
Using only a leather cleaner and a conditioner is like washing your car and applying a glaze. If you don't finish the job and protect the paint it will not repel dirt and grime as well, will need more frequent cleaning and will not hold up as well over time.
The best way to predict the future is to create it. Peter Drucker