I actually just had to do this. I bought a pieced suede hobo type bag on ebay, it's an older style and I had been searching for it for ages. I bought it cheap-around $50 and when it arrived the lighter colored areas were soiled-not terribly but I knew I needed to clean it up a bit. I worked on it yesterday and now she is as good as new, seriously! I can't show pics at the moment though because my year and half old son got his hands on my camera and I can't get it to work now, ugh!
Anyway, I used the suede cleaner from Applegarde, I diluted to half strength per the directions (in water) and then I cut a sponge into a small, manageable sized square. I dipped the sponge into the cleaning solution and rubbed the light patches in a circular motion. I didn't get the sponge soaking wet though. After I had done that, I used a washcloth dampened with plain water and just wiped those patches down-then I hung the bag up to dry. A few hours later I took it down and the patches that I had cleaned felt stiff as opposed to the soft suede of the rest of the bag. I used a nail file to touch up a couple spots that hadn't totally come clean. Then I used the Coach suede brush, the one that comes with the Coach suede cleaning kit, to brush the nap back up on those patches that I had cleaned. Once I did this, they became soft feeling again like the rest of the bag. I am carrying this bag now, looks gorgeous imho! Also, I have to say-this really boosts my confidence in buying suede off ebay since I now know that I can clean it up if necessary.
Oh, of course I also sprayed the bag like 3 times with Applegarde protectant after cleaning it up, lol. If you decide to use any kind of cleaner on a bag, just be sure to test it first to make sure it won't harm the color-and if you decide to use the nail file method, just be careful not to rub ALL the nap off your bag, and be really careful around any stitching so you don't fray the threads. Good luck!!