[violetpretty]

Even if you do change your dress code, what are you going to do if the same sketchy people come by dressed in a polo and khakis?

IMO, anyone who doesn't have their bedroom doors locked during a party can't complain if any of their property was stolen.

A guest list/showing a student ID with security is the way to go. This is standard at my school for registered parties. I don't know what your school's social policy is like, but if your chapter is having unregistered (illegal) parties, you can't very well hire security and expect not to get caught.