... and I have to say that he has such a Jewish mentality ...

- overheard just now in the foodcourt while on lunch, uttered by someone who was quite clearly not Jewish

As a member of an invisible minority, I am always intrigued when I hear things like this. What is a Jewish mentality? What exactly did the person mean by it?

If they had a conversation with me without knowing I'm Jewish, would they be able to pick me out as a Jew? What about after I told them?