many of the worst performances are ones, IMO, where they can't faithfully recreate on stage what was done in the studio.

Nathan Jones on Tonight Show - this is just an audio clip and the TS band is hideous. they sap every ounce of soul and coolness from the backing track. the girls sound great but it's awful overall

You're My Driving Wheel on Merv Griffin - again, it's hard for a tv studio band to recreate the power and massiveness of the recording. it just doesn't translate as well live

Let Yourself Go on Merv Griffin - this one translates a bit better live but the girls do SO much choreography that they're breathless. I appreciate the complex dance moves [[and won't say if i have or haven't learned them myself lol ) but the constant racing around impacted their ability to deliver the notes and harmony. plus in the studio they used an echo effect when they sang the title phrase in the chorus. they couldn't do this live so instead the girls are all randomly singing "go, go, go, go, go" and it's distracting.