Really a cool question friend. I played with my son and big sister the other day. Fun playing at 7,000 feet - the ball goes forever. The question came up at around the 12th; Is not keeping score illegal? Our winner of each hole would do a Jiggy dance pump our fist in the air and brag. Of course the same for a great putt or in my case the longest ball.
Most of the time on out of bounds the focus was on keeping the game going rather than etiquette or rules. I think we all took a Mulligan per 9 and one bonus.
Holding up the game as my son flirted and got a date with the beer cart girl was allowed as we let a "play through". A hearty rain on the 16th, and someone was not smoking tobacco in the anti-lightening spot.
My son and I were all wrinkled shirts and we saw one guy without on and another with a T-shirt. Music blared from our carts.
Well I reckon cheating was the least of our worries ;-)