I was in a deli years ago Paul Newman and a friend was eating there. People in the other tables were looking at him. Then they started to walk up to him talking to him while he was eating.
He was polite to all of them. He answered their question and even gave auto graphs. I was amazed on just how nice he was.
Thats because Paul Newman showed some class!
You can't buy class like that. A true professional.
I always find if you repect them, they will respect you. Let them enjoy their meal and if you must approach them after they are done you will get a better reaction.