WD-40 is like the magic sauce of everything. From oiling dry screws to cleaning stainless steel and inkjet printer cartridges, now you can use them to clean a particularly dirty or stained toilet if nothing else seems to work. Just use a little WD-40 in the water and it may be able to break down those stains.
You don't have to spray down the inside of your toilet with it to rid of the lime stains or discolorations, instead, give it a squirt or two and it takes a few minutes to break up and then add on the trust manual help of a toilet brush. You can also later followup with bleach, vinegar or whatever cleaner.
Have any other handy ideas on how to get rid of tough toilet stains? Do share!