When do you start looking like a fool?

When you're showing off, and you're not the one people came to see. At NEC last year, Mark Knopfler's rhythm guitarist was doing what presumably felt like him to be funky moving. In fact it looked painful. And it was even more painful since he was nothing but a distraction to the main attraction, who hardly moved the whole time. :-/

Re the "Fuck You, I'm Good attitude", if you don't have the confidence that you're worth listening to and you aren't enjoying playing, that's going to communicate to the audience who also won't get involved. That doesn't require dancing or running around or anything, but just demonstrating enthusiasm/enjoyment for what you're doing.

Re Britney Spears, I remember seeing her do "One more time" on the TV, years back, and I've never seen anyone with less stage presence than that. Sure, the dancing was slick and all, but it was utterly soul-less. And what more could the reviewer say, anyway? The girl can't sing, so the stage show is the only possible attraction.

Graham.