That's a great idea. Although i doubt it would be effective unless groups did it in a coordinated effort.
It does bring some questions to mind as to the legality of impersonating an officer of the law/civil protection/SWAT personnel but aside from those risks, if you get a large enough group of people doing that all together... well you've got yourself a civilian task force

I look forward to seeing swarms of faux SWAT personnel going door to door hunting down their next sugar fix this Halloween






