You can't selectively follow the rules when playing pool, and you certainly can't make up rules as you go along. An example...
Playing pool with my friend Jill, against my friends Craig and John (who once tried to pick a fight with Jaromir Jagr). Jill is not what you'd call a 'pool expert'. And by 'pool expert', I mean someone who can hit the ball straight. But rest of us can hold our own. At some point in the game, John doesn't have a shot, and all of our balls are at one end, so he pockets the cue ball on purpose. Now, because of the rules of pool, Jill now has to send the ball all the way down and back before it can hit one of our balls.
So I tell her to put the ball behind ours and tap it. Then they have no shot. She does it, and John shouts "BALL IN HAND! BALL IN HAND!" Apparently, the rule is that on a table scratch, the opponent gets ball in hand. Now that's fine. I think taking advantage of the one person who isn't good at pool is a bit prickish, but oh well, that's the rule.
THE VERY NEXT SHOT... the cue ball is resting against the edge of the table. John PICKS IT UP, measures two stick ends out, and puts the ball back down. Without another word he takes his shot. When I ask why he moved the cue ball, he claims that one is allowed to move the cue ball two stick widths from the edge.
POOL IS NOT MINIATURE GOLF! After a brief argument, in which his own teammate tries to tell him he's wrong, he throws the stick across the table, displacing all of the balls and ruining the game, and announces that he can't play with a bunch of people who don't know the rules.
OK, number one, we DON'T know the rules, but neither does he. And two, IT'S A FRIENDLY FUCKING GAME OF POOL. It's not the fucking World Series. But what do you expect from a kid who rooked his own dad out of twelve-thousand dollars?