The APA rule states that it is not a foul, the opponent has discretion to place the balls back where he/she "thinks" they were, and then the player that moved them retains the shot. I have had this situation occur to me in league play. My opponent placed the ball back where it was to their advantage. ie. placed a ball on the rail that was off the rail, or made the shot or out harder for me. In APA, from my experience, it is definitely to your opponents advantage if you move a ball. The rule also goes on to state that if there are a certain number of balls moved in a rack, it is a loss of rack. I think it is four balls.
Having said all of this, I shoot pool halls and gamble also. We play all ball fouls there and I definitely prefer that rule. But in APA there is a lower level shooter that is prone to making this type of mistake. There is also usually alcohol involved because it is a bar league. This is the fairest way to do things when people are out for fun in a bar and are not high level players.