They're scanning your Facebook Page; they're checking out the bumper stickers on your car. You got the wrong political "ties" some sweaty, unshaven guy from the alleged Greek mafia comes along and boots you out of the CPoC rally. I suppose that's alot easier than trying to convince you to vote for them.
PS. As a few people have noted, Harper and Co. spend more time vetting the kids that show up at their rallies then they do their closest advisers.