I'm goofy... and have no dominant eye. Whichever eye sees better through my glasses or contacts is what my brain uses as dominant. When I switch between glasses and contacts, it takes about about an hour to make the switch, and gives me a lot of "vertigo". I always knew something was up, but the optometrist confirmed it with me a few months back.
Fortunately, my glasses leave me with my right eye "dominant", I shoot right-handed with both eyes open, and wear glasses most of the time. When I wear contacts, my left eye sees better and becomes "dominant", and I have to close my left eye when I shoot.
But... to some degree, I always have double-vision, and the "dominant-eye" tests don't work on me, because I always see two of everything closer or farther than what I am focusing on.