How can any Catholic walk into a post-Vatican II parish and not see that it is not Catholic?

I think you're making this up. I've never seen a Rock n' Roll, Clown, Balloon, Dorito, or Disco M, and I've never heard of that taking place. Where do you get this stuff from? Quit lying. It doesn't look like a Protestant church, and there ARE statues of saints and the Blessed Mother, there is a tabernacle, and there are relics. You are flat out wrong.