Dixler, you are refering to
Rule #1 in Pedro's nude beach law.
If the woman is under 25 and drop dead gorgeous, there is only a 30% chance she will take her bikini bottoms off.
With a guy or a group of girls this can get up to 40% possiblities of full nudity
.
That is why I try so hard to shoot only pretty young ladies who are fully nude, I have a lot of wasted beach trips, but if I was happy shooting 50 year olds (which I cannot really get excited about), I would bring home hundreds of shots, every time!!!!