I figure Jewish people have as many variations as any group of people. Some very religious, some atheistic, and everything in between. To be honest, I've never had a good Jewish radar, if you know what that means. But the Jewish people I've known, have always impressed me.
No worries...I tend to get on the defensive right away because everyone just assumes if you're Jewish, your values went out the window long ago, which simply isn't the case. There are many people out there that claim to be Jewish but go against every aspect of the religion - and unfortunately they are the face of Judaism to most non-Jews.