I really only have one requirement for ginger beer. I have to feel it.
To wit: "...the ginger beer has to sting, burn, and fire up the back of your throat. You have to feel it in your nose and down your gullet."
I found such a ginger beer in Boston -- made by Goya -- and we used it in all our Black Gosling Dark and Stormys. It was spicy, opaque perfection. Once we moved out here and couldn't find hide nor hair of Goya, I quested for the perfect ginger beer. Nothing served. Not Bundaberg, not Blenheim, not anything you can possibly name. Believe me. I've tried them. ALL of them.
In Andronico's British food section, I finally found a ginger beer made by Belvoir, and it was good. It burned my nose and tingled my throat, and I was so happy with that sought-after sensation that I ignored the slight tinge of chlorine in the taste that became decidedly pronounced the more I drank.