An SCS is a custom Hop-up Nub that provides more surface contact when applying hop-up, therefore creating a more accurate shot.
In regards to the Hopup rubber washing, if you Lubed the actual rubber, take it out, and wash it with dish soap. Dry, and voila. This could also be caused by Lubing your mags, which would in turn lube your hop-up. Running a full clip of the Lubed BB's should wipe most of it away, and increase accuracy.