if the cue ball leaves the table but returns to the table is that consider as a scratch
I'm not sure what you're getting at, the term, scratch. However, in snooker, providing all other aspects of the shot are legal, the cue ball can leave the table, bounce all around the arena and return to the table, providing it ends it's move and stays on the table, it's a valid shot. It has been a long time since I've played snooker so I'm not sure of any changes in the laws of the game.
In International Snooker rules, a 4-point penalty is assessed if the cue ball jumps or leaves the table surface.
In Pocket Billiards, according to the Billiard Congress of America, a jump shot is only penalized under one of two scenarios; a) if the ball is intentionally jumped over an obstruction (ball or rail) or b) if the cue ball is intentionally struck with anything on the cue but the tip, causing the ball to jump. The first infraction in a match carries a warning; a second infraction in the same match results in forfeiture.
In 8-Ball, during general play with no formal referee, a jump( masse') shot is legal unless the obstructing ball is not a legal next ball and is touched by cue ball or cue. The penalty is treated as a scratch.
In Carom Billiards, jump balls are spotted.
I play in the APA, 8-ball and 9-ball. Although I don't have my rule books handy, I am pretty sure it is not. I have seen this happen (IE, while breaking the cue ball flies through the air, but when it lands, it lands on the other side of the table). No one has ever called a scratch when I saw this happen. However, I do know there are special rules about jump shots. I think these rules have more to do with the angle of your pool cue though.
If I am understanding your Question as the Ball runs a rail or atop of a rail and lands back upon the the felted play area it is not a foul or a scratch. If the Ball is scooped or is an illegal Jump shot it is a foul or a ball in hand depending upon which league you are shooting.
A ball in most leagues can Bounce out of a Pocket and return to the Play area and It is not a foul or a scratch. If The Cue ball at anytime is touched by anything, but the cue stick "Tip" this is a cue ball foul or scratch. If the Cue leaves the felted area and doesn't return to the felted area on its own power Ie. hits the floor, or makes contact with another player or sits and stays upon a rail it is a scratch.
Bar rules are slightly different wherever you are so its up too you to define the game before playing with some people.
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