its not sharking. -what is it with this sharking thing anyway.- if someone misses and un screws their cue most times its because they are mad and expect now to lose the game. they arent conceding anything. just like if you get mad and bang the table or kick your chair. you shouldnt be conceding the game. if someone does this and it causes you to now miss that is your fault and need to correct it.
sharking is someone doing something purposely to upset you or make you miss during your shot at the table.
tournaments have different rules and should be written or posted to all to see as they enter, otherwise the rule should not be enforced.