I'm having an upper g-i tomorrow morning, it will be my 4th or 5th one I've lost track over the years. I had my gallbladder taken out 14 years ago, hard to believe that much time has passed.
I've found that the barium tastes different everytime I've had it. They usually mix it with something to make it taste like strawberry or chocalate. It looks like a milkshake but sadly it doesn't taste as good.
It doesn't taste all that bad. I mean I wouldn't volunteer to drink it but I can think of far nastier things to consume.

)
Good luck with your test.
Antoinette