I have always associated the beer and tomato juice combo with being a hangover remedy. Also seems to be a south of the border thing, Mexicans like it.

I've tasted it and I don't think it is a drink meant for humans.

It also reminds me of a "shandy". I have never tried one but a guy at a beer store here explained it to me. It's when you buy a forty (doesn't matter what kind but I think a strong one would make more sense) and you cut it with some kind of soft drink, like ginger ale.

I think the idea is probably for hobos or people too young to buy booze to get more mileage out of their alcohol budget. And if I were desperate for a drink I would go for the shandy over the tomato beer (or mouth wash).

EDIT: a friend just told me that a proper shandy is made with 7up or lemonade.