This is an excellent question. As is often the case with “excellent” questions there isn’t a decent answer. 

When I was a nurse I had a boyfriend who was extremely debonaire and rather sophisticated. He worked for the BBC so obviously had an Oxbridge degree. Clever and fiendishly good looking he was highly articulate and bought expensive things. I had no idea he was a Marxist until he told me that my father was a fascist. A fact that had completely escaped me for 22 years.