There are plenty of people I see sign up for a weekly tournament I play in that have no idea about the rules. Watching someone who plays 8 ball with his friends using rules that were passed down from his uncle who played once in a bar in 1974 to playing with a bunch of B level players is interesting.
I've had people put the 1 not in front and then look at me like I was silly to suggest that it should be moved to where it belongs. Ball in hand anywhere and fouls are foreign terms, a foul is when the cueball goes in a pocket and that's it. I've once tried to explain playing a combination on the 9 using the lowest ball, first he lines up a shot right from cueball to the 9. I stop him "no you need to hit the lowest ball THEN that can hit the 9 in". So he goes to use the 2 ball as the cueball. Sigh....