In many pool halls they have wooden and plastic pool racks, always use the wooden ones. A plastic rack will flex and bend so by the time you pull off the rack the balls will shift unless you are very careful when lifting it off. When this happens you get a very loose rack so when anyone goes to break the rack it will not disperse equally or even worse the rack will not break at all. Any expert player knows this and a good tight rack will allow you to shoot high to medium speed and the ball should shatter all across the pool table. So when choosing your rack make sure you grab a wooden one, the reason most pool halls have the plastic racks is because of cost effectiveness but if you own your own pool table make sure you up grade to a goo thick wooden rack.
And as a note if a good pool player racks your pool balls and you strike them and they don’t break out well then there is only 2 reason for it, either it was a mistake or they purposely did it so they could have the next shot immediately. But its common courtesy for you to re-rack for your opponent if you give a bad rack.