Miss

A miss will be called if a player does not hit the ball "on" first and is deemed by the referee to have not made a good enough attempt at the shot. This gives the opponent the option of having the balls replaced as they were and have the fouling player take the shot again. A miss would not normally be called should either player require snookers, but there are exceptions. Firstly, it may be possible to make full central contact with a ball "on" with a plain straight stroke, in which case a miss would be called every time an unsuccessful attempt at hitting it was produced. Secondly, it is still up to the referee's discretion whether an adequate attempt at hitting the object ball was made. If the referee deems that the snookered player has made no genuine effort to hit the ball, a miss can still be called despite snookers being required.
The rule was introduced to prevent players from playing professional fouls (i.e., deliberately fouling so as to leave the balls in a safe position, reducing the risk of giving a frame-winning chance to the opponent). Multiple misses often occur because players attempt to hit a shot very softly or thinly in situations where a fuller contact might leave their opponent an easy potting chance. This can lead to an apparently easy escape being attempted several times, as players feel that it is better to concede many points but leave a safe position, than concede none and leave a frame-winning chance.
However, the applied interpretation of the rule has proved controversial, as players sometimes narrowly miss a shot many times. Sometimes this is due to bad luck, or the difficulty of a snooker, meaning that a good snooker can pay more dividends than a great pot.