The BS stays away when the quality of people (rather than quantity) increases. Usually done with a cover charge of some sort (must purchase food from restaurant allowing use of their parking lot, car show with prizes) or at the very least have it during the daytime.

Free gatherings in after-hours lots (ie: trespassing) by troublemaker teenagers showing off get shut down quickly. There is a *huge* difference between those "meets" and organized events.