They do know how to get their own way, don't they? Snoopy picked his spot in the kitchen, so we finally figured to just put the pad there. Who's trained? Haha!
Maybe you could put something in front of the sink when you're not using it, that would block her off, or be unpleasant to stand on. They make those bristly mats to put outside in front of your door to scrape mud off on.