What is a one-sentence summary of the following article?
If the leather is naked or aniline, it has no protective treatment, and will need to be cleaned by a professional. Wet a paper towel, and let one drop of water fall onto the leather. If it soaks into the leather instantly, do not attempt to clean it yourself. If it remains in a bead on the surface, however, the leather can withstand home treatment. If it is a fresh, still-wet stain, you stand a good chance of being able to nip this problem in the bud. If the stain is old and well set, however, the leather will likely need to be professionally re-dyed. Many leather objects come with instructions or a tag that offer instructions for cleaning. This may give you an idea of what will and will not work in removing a stain. Apply whatever cleaning agent you plan on using to an inconspicuous part of the leather object. It should be an area rarely, if ever, visible. Let it dry, and see how the leather holds up. Because time is of the essence with leather stains, if the stain is still wet, you may not want to wait for the spot test to fully dry before moving on to the actual stain. This is a bit of a gamble, so you need to weigh your concerns about doing further damage by cleaning against your concerns about allowing the stain to set. There is no single right answer, as the right course of action varies from leather to leather.

Summary:
See if the leather is finished or unfinished. Evaluate how old the stain is. Consult the instructions. Do a spot test.