Showcast Headshots

Let's just say there is a casting director looking for an actor to play the role of a gangster. When he/she goes through the actors database looking for people to audition, it would make sense to put a 'gangster' looking photo as my profile picture on showcast, but HOW am I supposed to know in the first place that they are looking for a gangster? How do I change my photos so that I give the right look to score the audition? Unless the casting director tells everyone they are looking for a gangster and to submit photos of yourself, then yes you can do it, but if the casting director looks for you based on your GENERIC headshot on Showcast, then spending money on multiple headshots is pointless. I don't think casting directors have time to go through your photos and detail and waste time deciding if you have the right look or not. Maybe a good idea would be to rotate my headshots every month and just HOPE that the right look matches what they are looking for at that particular point in time? Anyone have any other ideas?