Quite often I will see staff travellers with their ID on, wearing their civvies. A polite chat to the side about the importantce of discretion as a staff traveller usually brings them back into line though.
My partner who also works for the airlines was travelling on a flight one day, up the front in business. The pax behind was another staff member having an in-depth discussion about the rebated prices of staff travel business class tickets.
I was completly mortified when I heard that. A staff traveller having that sort of discussion with a full-fare passenger.
Totally unacceptable.