Listen to Buzzard. He's one of our resident knife experts. Anything more abrasive than Barkeepers Friend, such as Scotchbite pads or steel wool, will scratch the blade and make matters worse, probably requiring professional reconditioning.
Buzzard is also right about the patina that develops on carbon steel blades. It's a highly prized quality and you don't want to polish it off unless it's absolutely necessary.
I have a modest collection of high quality handmade knives, several of which are carbon steel. One, which I use as my carry knife in the field, is about 40 or 50 years old and has a beautiful patina. I clean it periodically with Barkeepers Friend. If I used steel wool or Scotchbrite on it, it would probably reduce the value of the knife by at least $200 or $300.
"Iím going to break one of the rules of the trade here. Iím going to tell you some of the secrets of improvisation. Just remember ó itís always a good idea to follow the directions exactly the first time you try a recipe. But from then on, youíre on your own." - James Beard