Answer:
Barkeeper's Friend sold in most grocery stores will rub away most stains, even the ones created by using a lousy toilet brush that has scratched the inside of the bowl - you just gotta turn off the water at the wall, fluch, then sponge out the water to get to the aluminum looking scratches. If it is a CALCIUM buildup, boiling vinegar or CLR cleaner may help.
Most cleansers, dropped out the abrasive when home builders started putting in these plastic fake marble countertops in the john.
Oh, if your plastic fake marble top bathroom countertop shows wear, scratches or has cigarette burns on the side near the bowl - do not freak out.
It can be refinished.
Go to an auto parts store and buy some RUBBING COMPOUND and some POLISHING COMPOUND and either rub the heck out of the countertop or get smart and buy a buffer.
.
Voila - looks brand new with a mirror like surface - just don't tell your neighbors the trick. Make 'em buy new countertops. (tee-hee!)