Question: How old is too old for a see-through silver outfit to ever be appropriate?
Answer: It's never appropriate! I wouldn't care if this was Liza Minelli or Lily Allen, it's still going to look blooming ridiculous. Most likely this outfit was only see through for the flashes of the paparazzi cameraa. BUT THAT'S THE MOST IMPORTANT PART. Someone like Liza, who's been around simply forever, should know that the cameras would have been a-snapping and catching her out.
She has a cameo in the movie btw.