"...when you guys aim wrong," oh, no doubt...but us guys can't take all the credit. Many years ago I kept company with a lady whose apartment was spic & span....except for under the toilet seat & rim. She, of course, never lifted it...even when she cleaned, evidently. I was, to put it mildly, startled by how bad it could get, and I have seen similar situations since.

Toilets require work...and I figgered out the razor blade trick in self-defense, as simple chemicals, as far as I can see, won't prevent gradual build up of stains. So every year or two, I take an hour and get 'em CLEAN!