I know many of us face this problem, but I have a SNES in box and the power supply has a lot of this damage on there. It's like melted on the cable over time. I actually bought it like this and didn't know until it arrived. It was a few months ago but the console was A-1! Is there any way to remove this or decrease the effect? For future notice, how can you prevent this?
To prevent anything from happening to cables, just place them in ziplock bags. I've gone a bit crazy with them in the past year or so, and now I have everything stored in them! Cables, pads, ac adapters etc.. even my CoreGrafx Nothing gets tangled anymore!
I hate when people put tape on damaged controller cables. It doesn't work properly and goes manky. Real sleeving isn't that expensive and works far better because you actually use heat to seal it.