I don't think I would ever presume to call anyone anything other than Mr/Mrs/Miss or Sir/Madam.....unless they then tell me otherwise.
However, I have to say the last name badge I wore had my first name and surname on and I wish it hadn't had both. Poor STS has utterly unpronouncable surname, so pax would flounder in attempt at using it, not bother and call me nothing at all, or just use my first name anyway. I seemed to spend more time teaching people to pronounce my surname than doing anything else.
If they called me dear or love, I was very tempted to check their bags in to Cleveland...