I was flying in CW some years ago, sitting in the aisle seat of the centre four. The middle pair had two ladies in it. A third lady came down from First and swapped with one of them and started going through a folder of publicty shots. The woman was Natalie Imbruglia. She swapped back before the meal service though. I had no idea who she was until some friends of mine who happened to be on the flight told me!

So maybe it depends on how famous you are!!