Yup, as J-P says, a good soap and water cleaning with a soft bristle tooth brush will remove a lot of the material that you've mentioned. Then, after washing, you can see if something more is needed.
A lot of people feel pretty strongly about keeping the "fish mojo" that's usually pretty evident on the cork of a well-fished rod. But I like mine a little more on the clean side.
If, after washing, you want to go further, then here's how I do it.
1. If you want to leave the surface of the grip intact (or close to intact), then get yourself some fine bronze wool. Mix in a good detegent with some abrasive in it (I use a product called "Soft Scrub") and give it another wash. Don't bear down hard; let the abrasive and the bronze wool do the the job for you. Usually, this is all it takes for me. [Here's another thing that works for me as part of the cleaning sequence. Wet a paper towel and wrap it around the grip several times. Leave it in contact with the grip overnight, then proceed with the bronze wool/detergent wash. Most of the fish slime, minus the small dirt particles, is water soluble. The wet paper towel softens up this material and makes it easier to get it off with the bronze wool washing.]
2. If you don't mind removing the surface cork from the grip, then as a second step, get yourself some #400 sandpaper (I've used all the way down to #700, but that's the slow boat to China if you're serious about removing the surface coat of cork from the grip). Wrap it around your finger so that it's curved and use a gentle forward an back motion to get the surface layer off. I use long strokes; from the tip of the grip to the end and back; turning the grip very slightly with each pass. This removes the minimum amount of surface cork; which is probably what you want to do. If you in advertently create micro-ridges with this motion, then as a finishing step, wrap a band of the sandpaper around the grip and sand lightly around the grip by turning the rod with your other hand; not back and forth. This should give you a grip that looks "almost" new.
3. If you need more, then go to a coarser grain of sandpaper. But with the coarser materials you run a higher risk of destroying the shape of your grip, which will just push you into replacing the grip or having to live with a grip that has a feel that you don't particularly like; which generally means that you'll fish the rod less. [Another downside to using coarser paper is that you then need to use a finer paper to get the smooth surface effect that you're looking for and each step introduces the opportunity to do something wrong. So, overall, fewer steps, in my opinion, is much better than more.]
Magic erasers and other eraser abrasives also work; they serve the same purposes as the sandpaper.
It's all a matter of personal taste.
Pocono
