To get a good crowd it is the best to get a good security not letting people to be so neglect to the rules of the club. DO NOT LET the people to inappropriate things. Make rules. And get an experienced security and face control.
change the style of music, dress code or who your promoters are
avoid playing the kind of music that your 'bad crowd' prefers, bring in different promoters that have better crowds, deny them at the door.