Years ago, I had read some information about a parrot owner who so strictly "potty trained" their parrot [I don't think it was a Grey] that it died because it had been out of it's cage so long and hadn't been given the command to "potty" in a humane time period. I can hardly believe that someone just made this story up but who knows?
One thing we did with Corey was to train her with the request: Go Potty. We did this by saying Go Potty whenever we saw her doing the "potty dance" and then rewarding her [when she went potty] by saying: Good Bird! The way that this helps us is that when we take her to any place in our house where we can't easily clean up a potty, first we take her to her cage [or any other place where she is comfortable going potty] and ask her: Go Potty. Often, she will go potty for us and then we know we have around 15 minutes where we know we are probably safe. If she doesn't go potty when we ask, it's not a big deal. We don't press the issue. It's not a perfect solution but it's something.