In one of my favorite clips from Sullivan, with Paul Revere and the Raiders, it’s very obvious that Mark Lindsay is singing live by the way his voice fades in and out as he moves his mic around. It’s also obvious the Raiders are playing to a pre-recorded track. For one thing, there are no cords coming from the electric instruments, and for another, there’s a very poorly made chop at the end of “Him or Me.” The chop at the end of “Kicks” is better, but still sounds like it was added by someone else.
This is the problem when all your records were done by the Wrecking Crew, and people expect your live performances to have the same sound.
One of the most bizarre lip-syncing combinations was The Dregs on American Bandstand. You’ll probably never see a better group of musicians pretending to play there instruments. Might be the only time Mark O’Conner finger-synced his fiddle.