Down play

I was watching an interview down at Plan Fallon where the interviewer starts the conversation by telling people that what is to follow isn't likely to be very good. It makes me wonder, would it be so bad to start something by telling your audience what they are about to see is going to knock their socks off? I guess it would. It would raise expectations. How, when and why did optimism become naff? Zeitgeist. (Don't worry, I just threw that in for effect.)
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