Water marks/heat scars and white rings
Massage mayonnaise into the marks and leave it on overnight. The next morning, wipe off the mayonnaise and the marks should be gone. You can also use petroleum jelly, butter, or margarine. If you have a really stubborn spot, mix cugarette ashes or rottenstone (hardware store) with the mayonnaise and repeat the above procedure.
Non-gel white toothpaste is also effective in removing water rings. Dab toothpaste on a damp cloth and gently massage the ring in a circular motion until it's gone. Wipe and buff with a soft cloth. Apply furnature polish if necessary.
This is out of "Talking Dirty with the Queen Of Clean" Linda Cobb.
Hope it helps. Never done it myself.