Thanks very much for taking the time to read my post, Abu Noor.
Oh--okay--JFK is a bad Catholic
in the sense that he doesn't uncritically accept all Catholic theology, doesn't attend Mass every Sunday and doesn't recite prayers with acceptable roteness.
Today it is more widely acknowledged that there is extreme diversity in belief, among Catholics--and that almost no one accepts church teaching hook, line and sinker.
Once you disagree with the Catholic Church on any tenet, you have no right to malign a coreligionist a cafeteria Catholic
The sense in which Jackie O is said to have called JFK 'a bad Catholic', then, lends itself to easy confusion today, since almost no one uses the phrase that way anymore.