"positive and abundant" messaging brands are not brands at all, they're defensive marketing postures that do no good, but do no harm either. It's the brand equity equivalent of a zero interest money market fund. brand equity is proportional to brand risk.
I think the fast food chains have been getting good at the game slowly, trolling each other and occasionally the consumers. Most of the good examples are in political brands where the downside risks are mitigated because you don't care about the other half of the voters anyway.