I always cleaned my track before operating sessions and after I finished and usually I had a pretty significant amount of gunk I would wipe off the rails. Well let me tell you all that after a running session my rails usually wipe mostly clean, so much so that I quit doing the post-run wipe down and I only clean before runs now. I do have just a few tips for the first time user to keep in mind: 1. Make sure the rolling stock you attach it to is small enough so that the pad can clip over it without causing too much rolling resistance. Rusted steel axels are a no-no and you locomotives will have a hard time pulling the train. 2. If you soak the pad in rubbing alcohol before running the train, the cleaning efficiency is 10x's better. 3. And this is the most important, these pads DO NOT work well at all on steel tracks. Unfortunately if you have steel track, good old fashioned abrasive cleaning and elbow grease is still all you can do or buy an abrasive track cleaning car. These pads DO work on nickel silver track. I unfortunately do not own any brass track so I cannot report on the effectiveness there although it may work if used very frequently. 4. The pad surface is made out of felt, you may be able to get more life out of your pads by cleaning them with a dish detergent but I haven't tried this yet. All in all, these things are pricey at $11 per 5, but so very very worth it. I will recommend these things again and again to anyone who complains to me about dirty track.