We brought a bottle of Pepsi and coke from Washington state, Canada and Alabama. And with one of us only pouring into glasses we tested each.
Conclusion: side by side we couldn't tell the difference really. We did conclude that coke has more canonization and that Canada coke and Pepsi are way sweeter then the others. We also thought there were probably differences in the taste in cans and fountain drinks as well.
It was great fun for an evening of laughs.