if you look closely were the z-rims are originally removed after they have been made, (normally white lines about an inch long in centre of rim in 3 or four places) there tends to be slight file marks suggesting that they with stand sanding/ light filing etc..
I cleaned mine with wet and dry... to remove brake rub etc and it worked fine, depends on how deep the scratch are because eventually you will begin to change the profile shape of the rim.
somebody said, use a thick car polish the stuff that is coloured, similar to the rim colour to fill light scratches in the same way it does in cars paint work that has been marked. Never went that far myself....
yellow z rims, sounds cool!