A friend one time was upgraded to a verandah room, they had booked a room with a porthole window (don't know specific categories).
DCL called her a few weeks before the cruise to give her the "good news". Which was not good news at all to her - they specifically hadn't booked a verandah because they had a toddler who was prone to climbing. So she made them change it back, but it was a big ordeal and took several days to get their original room back and several CMs were apparently less than polite about it.
Honestly, I'd be a little annoyed too to be "upgraded" without being asked first. I researched for many hours and specifically chose our stateroom because it was the one I wanted.